Author Topic: DMMCheck Plus Multimeter Reference(and other References) - Experiences..  (Read 31903 times)

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Offline Fungus

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #25 on: July 04, 2023, 06:16:28 am »
Having said all that, Doug is a good guy making good products, so I'd say if in doubt but you can afford it, go for it.  :)

Yep. Doug will obviously give you a garantee, etc.

 

Offline iMo

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #26 on: July 04, 2023, 07:40:33 am »
First step when buying such a reference box is to look at its schematics. While doing so you'll get what the parameters really are. Most notably the reference chip and the resistors around the reference are the key.
Readers discretion is advised..
 

Offline KungFuJosh

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #27 on: July 04, 2023, 03:05:48 pm »
The hardware in those devices seems OK, it's the calibration where some sellers are cutting corners.

100% - and that's the most important part. None of them are that expensive, but buy the time you buy them all to find one that's accurately calibrated and labeled, you might as well buy something nicer. I did read reviews, but people are often clueless, or fake.
"Right now I’m having amnesia and déjà vu at the same time. I think I’ve forgotten this before." - Steven Wright
 

Offline Fungus

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #28 on: July 04, 2023, 06:09:54 pm »
The hardware in those devices seems OK, it's the calibration where some sellers are cutting corners.
100% - and that's the most important part. None of them are that expensive, but buy the time you buy them all to find one that's accurately calibrated and labeled, you might as well buy something nicer.

Seems like a business opportunity for somebody with a decent DMM. Buy them cheap, calibrate them, sell them a bit more expensive. :popcorn:

 
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Online Martin72Topic starter

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #29 on: July 04, 2023, 06:25:18 pm »
Calibration is a kind of "official" confirmation that a meter is in it´s own specs.
If you have a cheap meter with lousy specs calibrated, you have official confirmation that the meter is lousy.
Great...

Online Martin72Topic starter

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #30 on: July 04, 2023, 06:49:45 pm »
So now it's on, I just ordered the DMM reference with L/C option.... 8)
Should arrive this week.
Voltage, current, frequency, resistance, inductance, capacitance. ,optics, what is in papers with it..... I will then test and report here of course.
 
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Offline Fungus

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #31 on: July 04, 2023, 06:51:04 pm »
If you have a cheap meter with lousy specs calibrated, you have official confirmation that the meter is lousy.

What if you have a cheap meter with really good specs?

eg. https://lygte-info.dk/review/DMMAnengAN870%20UK.html
 

Online Electro Fan

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #32 on: July 04, 2023, 07:04:53 pm »
Those random examples are all trash.

I've measured mine on various multimeters and it seems legit.

There were quite a few in that thread I linked to that were legit, too.

The comments above regarding how accurate they are and continue to be are pretty consistent with my experience.

I bought 3 of their products way back in the day and was/have been happy with all of them (two are marked 2011-12 Rev 1, and one is 2008 R4).

The hardware in those devices seems OK, it's the calibration where some sellers are cutting corners.

I'm sure you can get a good one if you take the time to go through all the Aliexpress comments/ratings. I just posted a few random listing to give an idea of prices.

nb. The references in them are probably pulled from old devices. The silver lining is that they'll be well burned-in.  :)

Just to clarify/confirm....

When I said:

The comments above regarding how accurate they are and continue to be are pretty consistent with my experience.

I bought 3 of their products way back in the day and was/have been happy with all of them (two are marked 2011-12 Rev 1, and one is 2008 R4).


These ^ are all references to the voltagestandard.com and DMMCheck Plus products.  5V Reference was 2008, PentaRef was 2011, and DMMCheck Plus was 2012.
 

Online rhb

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #33 on: July 04, 2023, 07:57:53 pm »
If you have a cheap meter with lousy specs calibrated, you have official confirmation that the meter is lousy.

What if you have a cheap meter with really good specs?

eg. https://lygte-info.dk/review/DMMAnengAN870%20UK.html

I tested 8-9 "Free with any purchase"  Harbor Freight DMMs which sell for  $5-6 now.  They were all in spec and I adjusted them all to <0.1% ( the limit of resolution for a 3.5 digit meter).  Unless I'm at my bench with dual 3478As and 34401As, I'm most likely to use one of those.  I'm probably down to 3 or 4 now.  I got them to give away.  Dad and I bought slew of them for $2 on sale before they started giving them away.

I have them in many places and toolboxes.  If needed I have 4.5 digit Tenma bench DMM with an internal battery pack for portable use.  But having a DMM in the dry cell drawer is very handy. 

I feel very confident that anyone buying one of Doug's products  will be very pleased.

Have Fun!
Reg
 

Offline jchw4

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #34 on: July 05, 2023, 08:28:40 am »
So now it's on, I just ordered the DMM reference with L/C option.... 8)
Should arrive this week.
Voltage, current, frequency, resistance, inductance, capacitance. ,optics, what is in papers with it..... I will then test and report here of course.

Could you share your calibration certificate that you receive with it?
I got mine long ago from voltagestandard.com and could not be happier. But after the project was sold to the new owner and since then my experience was not as good as with Doug. I added the LC option and I don't feel strong about it.
 

Online Martin72Topic starter

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #35 on: July 05, 2023, 09:30:19 am »
Will do when it's here.

Offline J-R

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #36 on: July 05, 2023, 10:33:02 am »
What is your concern with the L/C board?  One thing to note is that the values are taken at 10kHz.  Early printouts did not state that.

Here is a calibration sample from their website: https://img1.wsimg.com/isteam/ip/c544540f-524c-4b38-8d0c-cbfda88bf37a/blob.png
My printout from 2022 looks the same.
 

Offline tomud

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #37 on: July 05, 2023, 09:15:18 pm »
If you have a cheap meter with lousy specs calibrated, you have official confirmation that the meter is lousy.

What if you have a cheap meter with really good specs?

eg. https://lygte-info.dk/review/DMMAnengAN870%20UK.html


Currently, most even cheap multimeters have very good accuracy, be it Aneng or UNI-T... However, when it comes to the meaning of the term "multimeter calibration", we must first establish what we mean by it. Unfortunately, in many countries certain procedures have different names and some confusion can arise here.

Heh... I could even mention UNI-T multimeters, which when new are sometimes better than BM869 or other multimeters of this class (if we talk about accuracy)

For example, a relatively cheap multimeter calibration can be performed and can either consist of programming the calibration data into the device so that the multimeter reads correctly. We can also receive a printout on which the multimeter is compared with the reference equipment - then using, for example, the table we have, we can manually calculate and correct the indications. We can, for example, do something like this for private use. This is only a calibration and we do not get a certificate

There are also cases, most often in companies where we need a certificate (this is defined by the relevant standards ISO etc.) from an accredited laboratory - such a document has a certain legal force and most often such a procedure is more expensive than the so-called. "calibration".

Going back to those cheap multimeters, the device is accurate, and even if we pay and get a certificate for the device (which must be renewed periodically), there is still the question of how much we can trust the multimeter in the intervals between certifications. Unfortunately, the accuracy of multimeters is not everything and as I mentioned when the equipment is new, even the cheapest ones are in most cases very good.

The problem is, unfortunately, that here we can never be sure how long the multimeter will keep these good parameters, unfortunately in the case of cheap multimeters it does not look so good. In such cases, it is worth having not so much as some reference sources, but a better quality multimeter with which we can periodically check such cheaper equipment whether something is broken and does not show measurements very distant from reality.

This is an example from my experience. For example, one of the multimeters I use more often is the Brymen BM869S - bought over 5 years ago. The equipment is heavily exploited, it has had several falls to the ground from a greater height. I don't treat him like an egg either. In fact, although the housing does not look so nice anymore, the multimeter still maintains the declared parameters, and the multimeter did not require calibration (saving calibration data in the eeprom memory).

Unfortunately, it is not so beautiful with cheaper multimeters, e.g. wear of a rotary switch or poor quality sockets (cheap metal plates) is already starting to affect the measurements, and their accuracy has deteriorated significantly. Currently, they are more suitable as an "indicator" to check whether there is voltage or not :)

Here in all this the most important thing is the awareness of all this, not whether we have this type of "calibrator" or even a certificate.

Personally, I prefer to use 6 1/2 digital meters to test the cheaper millimeters - this is where I feel more confident about the procedure. Why ? It's unlikely that all three of my lab multimeters will suddenly fail or lose their performance. So even if one breaks, I'll be able to spot it very quickly.

Their accuracy is just as more than enough to be used as standards for cheap multimeters, I don't need an 8 1/2 multimeter to test multimeters 4 1/2 digits and below.
In fact, this is a more reliable method of evaluating multimeters than certifying a cheap multimeter or having a single reference voltage source (which can also fail).

Of course I have some Chinese reference voltage source. However, it is not used as a reference source, but only as a time-stable voltage source - which is also sometimes useful in testing. Knowing the exact voltage of this source is not the most important thing here.

« Last Edit: July 05, 2023, 09:27:01 pm by tomud »
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Offline rsjsouza

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #38 on: July 06, 2023, 11:03:10 am »
My experience reflects tomud's as well; the various cheaper multimeters are indeed quite accurate but only until the point of wearing their mechanical components (jacks and mainly rotary switch). Surprisingly my old UT61E has been holding itself quite well, but it hasn't suffered any major falls (for the hard work I have an old brown Fluke 27/FM).

As I learned a long time ago: it is easy to make a product that works; it is much harder to make a product that works AND has endurance.
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Offline Svgeesus

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #39 on: July 06, 2023, 05:04:30 pm »
However, it needs to be shipped off for a yearly calibration to be of much use, IMHO.  It is going to drift a little over time, and my calibration data reflects that. 

How much drift do you see?  I can't imagine using these for anything beyond the 4.5-digit level--am I wrong?

I bought a DMMCheckPlus 10 years ago, and a couple of years ago I sent it back for recalibration. Both the original cal and the recal were done with an in-cal 8.5 digit meter, and the drift was substantially less than one would expect based on the Vref datasheet.

My meter is 6.5 digit and out of cal for 5 years so I can't compare my readings to his with any confidence. But I am happy to trust his cal certificate.

I also find that having DC V, AC V, current, frequency and resistance all on the one unit to be great as a sanity check before any sort of reading on my main meter.
« Last Edit: July 06, 2023, 05:09:14 pm by Svgeesus »
 

Offline Fungus

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #40 on: July 06, 2023, 05:09:12 pm »
... the multimeter did not require calibration (saving calibration data in the eeprom memory).

Around here that would be called "adjustment".

"Calibration" - measuring reference values and producing a report.

"Adjustment" - modifying the device to improve the accuracy of the displayed values.

My experience reflects tomud's as well; the various cheaper multimeters are indeed quite accurate but only until the point of wearing their mechanical components (jacks and mainly rotary switch).

I've only had one meter go bad (via the rotary switch) and it was obviously bad, ie. It didn't display sensible values.

If you're going to be dropping it from ladders on a regular basis then it obviously makes sense to buy a decent meter and the cost probably won't matter - you're being paid to be up that ladder.

If you're working with dangerous voltages then "trust the meter" isn't enough. You should own a proving unit (and use it).

https://www.fluke.com/en/product/electrical-testing/basic-testers/prv240-proving-unit

I assume all the meter nannies around here do that, right?

If you're not throwing it off rooftops and/or working in arc flash environments then how much is this is relevant? A meter that doesn't work will be found out in minutes. Just bin it and grab one of the others.

(and as noted, this is very infrequent in my own anecdotes)
 

Offline Svgeesus

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #41 on: July 06, 2023, 05:15:20 pm »
Oh and also to mention excellent customer service.

Quote
Chris,

I forgot to mention that I updated the firmware in your DMMCheck Plus microcontroller.  You can now switch between the two frequencies by toggling the AC/DC switch from AC to DC and back to AC- you no longer have to cycle the power to the unit to get the second frequency.

Regards,

Doug
 

Offline Veteran68

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #42 on: July 07, 2023, 12:32:57 am »
Before I hit the buy button, what are your thoughts ?

Have you seen these?

https://www.aliexpress.com/item/1005002190676191.html
https://www.aliexpress.com/item/1005004219629979.html
https://www.aliexpress.com/item/1005004221641169.html

(random examples)

Those random examples are all trash. I bought them (thankfully they're inexpensive trash 😉). Most of them don't come with any reference values written. NONE of them come with any form of certification for the values written. The one unit I received that had values written, was mostly bs. I think 3 out of all the written numbers were accurate (checked across multiple meters with higher digit counts than the reference numbers).

The only value for any devices like these are if you know they're measured/calibrated from a reliable source.

I have a few different varieties of these for both voltage and LCR references, including the one that takes the weird 10F2015 15V battery, and they all came with written values which checked out according to my Agilent 34401A. Most if not all came from Amazon but don't know that that makes them any more "legitimate" than an AliExpress seller.
 

Offline KungFuJosh

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #43 on: July 07, 2023, 12:38:31 am »
I have a few different varieties of these for both voltage and LCR references, including the one that takes the weird 10F2015 15V battery, and they all came with written values which checked out according to my Agilent 34401A. Most if not all came from Amazon but don't know that that makes them any more "legitimate" than an AliExpress seller.

I think it's a roll of the device depending on who you get them from. I tried a voltage ref from Amazon, and it was pretty darn close to the marked value (like within .0001)...but also died the second time I tried turning it on.
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Offline all_repair

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #44 on: July 07, 2023, 03:15:25 am »
Before I hit the buy button, what are your thoughts ?

Have you seen these?

https://www.aliexpress.com/item/1005002190676191.html
https://www.aliexpress.com/item/1005004219629979.html
https://www.aliexpress.com/item/1005004221641169.html

(random examples)

Those random examples are all trash. I bought them (thankfully they're inexpensive trash 😉). Most of them don't come with any reference values written. NONE of them come with any form of certification for the values written. The one unit I received that had values written, was mostly bs. I think 3 out of all the written numbers were accurate (checked across multiple meters with higher digit counts than the reference numbers).

The only value for any devices like these are if you know they're measured/calibrated from a reliable source.

I have a few different varieties of these for both voltage and LCR references, including the one that takes the weird 10F2015 15V battery, and they all came with written values which checked out according to my Agilent 34401A. Most if not all came from Amazon but don't know that that makes them any more "legitimate" than an AliExpress seller.

All of mine were as good as they were specified.  These are not something that low-ball sellers are interested.  Firstly volume is not high, and secondly buyers are of a higher level that the sub-standard goods can get away easily.
 

Offline tomud

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #45 on: July 07, 2023, 06:59:02 am »
... the multimeter did not require calibration (saving calibration data in the eeprom memory).

Around here that would be called "adjustment".

"Calibration" - measuring reference values and producing a report.

"Adjustment" - modifying the device to improve the accuracy of the displayed values.

It's not like we call something a given procedure in our own way. It's about what nomenclature is used officially in different countries because unfortunately I don't know.

For example, in Poland there are two words that translate to the same word calibration in English ("wzorcowanie", "kalibracja")

The concept of calibration ("kalibracja"), for example in Poland, means setting the multimeter, if possible, that is, saving new correction data to the device, and if the equipment does not have such a possibility, providing a comparison table with the reference device. This is usually a much cheaper service that I personally use on hobby equipment. For example, the cost of such a service at the authorized distributor of Brymen in Poland (Biall company - have their own accredited laboratory) - i.e. calibration consisting in saving calibration data to the eeprom memory of the multimeter is about 45 euros + VAT.

There is also such a service performed in accordance with the ISO 17025 (PN-EN ISO/IEC 17025) standard, it costs more. This is called calibration ("wzorcowaniem" - written in Polish) by issuing a  "certyfikat wzorcowania" (written in Polish). Translating into English and German (but I don't know if it's a correct translation): "calibration certificate", "Kalibrierschein"... Such calibrations must, for example, be performed by ISO-certified companies.

Therefore, when writing about calibration here, there may be some misunderstandings due to language differences. So if we are talking about some documents issued by accredited laboratories, it is worth mentioning whether they are in accordance with ISO 17025 or is it just a simpler service of setting / comparing the multimeter with the reference.

-------

Coming back to cheap measuring equipment. It's ok, you can buy one (I recently bought such inventions as Aneng A3008 and A3009 - but I will use them more as an indicator of whether there is voltage). However, keep in mind that this accuracy may change over time. Similarly, in the case of such multimeters, quality control is practically non-existent, so here too there is a chance that we will receive a new multimeter that, due to some production problems, does not meet the expected parameters. Such multimeters also have other shortcomings. For example, the mentioned Aneng AN870, despite good parameters, has "shallow" sockets. So better cables, e.g. Brymen/Fluke, etc., do not fit it.

« Last Edit: July 07, 2023, 07:40:34 am by tomud »
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Offline J-R

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #46 on: July 07, 2023, 08:19:40 am »
The International Vocabulary of Metrology (VIM) was first published in 1984 and has had many revisions since.  The VIM of course pushes the separate definitions of calibration and adjustment among other specific terms, but it's not a guarantee that everyone just adopts such things immediately.  Plenty of older manuals consider calibration to include adjusting the instrument if necessary, and I still see this used in modern times as well:  https://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-2-mini-detail

So probably best to not get too bent out of shape on it.
I personally try to stick with the terms the manual states when discussing that product or repairs, just to be consistent.
But otherwise I'm happy to explicitly state such things as calibration/adjustment/data or etc. just to be clear.

With that in mind, my understanding of the DMMCheck Plus "re-calibration" procedure is: an adjustment of the voltage reference to be as spot-on as possible; a small drop of adhesive is applied to the trimmer pot; gather measurements of all references/standards; data printed.  I have never seen the "as-received" calibration data for the voltage reference but I am pretty sure they do perform that and perhaps it is available upon request.

The "recalibration" of the DC voltage references from VoltageStandard.com is also the same.  All the references are tweaked to be as close to the desired value as possible before being sent back to the customer.
 

Offline mendip_discovery

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #47 on: July 07, 2023, 01:33:36 pm »
Things like this are handy as a check, much like if you use a weighing scale to measure products all the time it's handy to have a calibration weight to check it monthly/weekly etc. Engineers keep gauge blocks handy as a way of checking tools.

I would be happy to use a unit like that to check a home multimeter of 5.5 digits or less. It might be a bit of a challenge for a 6.5 or 8.5 as they are much better than the specs of the DMMCheck.

There is nothing worse than having 2 meters disagree on a measurement to the point where it's hard to determine if it's the thing you are measuring or the kit you are using. Having a sanity check comes in handy then.

Cheap vs Expensive, my experience has been expensive 1 out of 10 might have an issue or two, but a cheap meter 1 out of 10 might actually be rather good. YMMV. As I noted the other day the RS-14 is rather crappy when its battery starts to get low, even though it doesn't tell the user.
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So everyone is clear, Calibration = Taking Measurement against a known source, Verification = Checking Calibration against Specification, Adjustment = Adjusting the unit to be within specifications.
 

Offline bdunham7

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #48 on: July 07, 2023, 03:16:21 pm »
The "recalibration" of the DC voltage references from VoltageStandard.com is also the same.  All the references are tweaked to be as close to the desired value as possible before being sent back to the customer.

FWIW, Doug puts the as-received value on the certificate as well.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Online Martin72Topic starter

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Re: DMMCheck Plus Multimeter Calibration Reference - Experiences ?
« Reply #49 on: July 07, 2023, 03:29:26 pm »
Should arrive this week.

Has arrived... 8)

Tests will follow in the next days, with my brymen BM869s, East Tester ET4410 LCR Bridge and...
..Two scopes, a 8bit and a 12 bit from siglent(SDS1104X-E and SDS2504X HD which is known for it´s accuracy)
Could be interesting..
 
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