Safety of this meter and those like it has been discussed in depth by others, the main point is not to use it on mains or any device with risky voltage/current potential inside.
With that said, I can ask the other question I had, how much do you have to spend to get that coupon?
I'm just curious, as sometimes "free" is not free. For example, if the price of items purchased is already sufficiently higher comparing to other stores that sell the same thing, that even considering the value of the "free" item, you ended up paying the same, or more. Of course I don't know if that holds up in this case, sometimes it happens.
That said, there are many variants from China, and they can differ in functionality and even build quality. They don't normally have the "on off" switch (off is on the range switch), at least I haven't seen it in any product image.
When searching for some info a while ago, I found this page:
http://all-sun.com/manual/Dt830_en.pdfFrom the document above, here are the differences in some versions:
I have one of these, it comes with the continuity test beeper, and no (obvious) fuse inside or a fuse holder (but maybe the newer revision has a fuse, who knows):
It is less than $3 on eBay.
The main point of failure seems to be the probes. The wires are not properly supported, and can break and come out. The best moment to know about this is before the meter is used.
If the probes on the meter you get with the free coupon look exactly the same, then adding some hot glue before the first use can be a quick (although perhaps not permanent) fix:
What others here have showed me is that you can (with pliers) disassemble the probe/take out the needle part, and then properly attach the wire to the pin so it's held in place firmly, and maybe add heat-shrink for support. But adding some elastic glue to the end as support is definitely the easiest solution, just not the highest quality one.
One positive thing about these meters is the display contrast. It is really great and easy to read from most angles.