Works great - Trijicon ACOG 4x32 Flip Cap Set (Requires TA91 killFLASH)

So, I have not had any of the problems I have read about this product. The objective lens cover easily went on the killflash. The ocular lens cover was significantly more difficult to instal. I recommend heating up the lens cover by immersing it in hot water for about 5 minutes. Then place the cover on your countertop or workbench and press the ACOG into the cover. I was nervous when I did this as I didn't want to damage the scope. Take it slow and perhaps put some padding under your workplace. Luckily mine went on straight and I have no problems with the flip cap staying closed. For the record I put this on a TA-31F with the bosses on the eyepiece.