I got 4 sets of each size of lens awhile ago. Been busy integrating my Autoliv2 controller to try them out extensively and look at them.
All of the small ones appear to be 7.5", one is labeled and holding them up side by side to the light the "focusing point" when I get the smallest point of light below them all appears to be the same distance. The larger ones all appear to have the same focal point as-well. But I have no labels on any of them. 3 of them have the RFID puck but I don't know if I have an RFID reader for them handy.
The small ones work GREAT for getting an extremely close focal point on the Autoliv2, I had previously screwed out the lens a bit to get it to about 2~ft but you end up with distortion from the way the lens is in the Autoliv... Without setting that back and just throwing the lens in front it really clears it up and just yea wow. You can see below how far I had it from my board and what it looked like on video. (this is with histogram and an iron palette mind you, this is not what cames straight out of the camera) Frankly I didn't have the focus perfect... Trying to take a photo of what I was doing while holding it was a bit difficult. Will eventually try to 3D print an adapter for the Autoliv2. I will note I am not keeping all 8 lenses... 4 of them are going off to friends, I made a bulk order to the US to help save on shipping for us all.
I will say these look clearer on video than the germanium protective covers that come on the Autolivs. Really nice lenses especially for the price.
All of my lenses appear in great shape. With only a few minor spots on some of the smaller lenses and the large ones look almost perfect.