This lens fits on both, NVG50 and NVG30, it expands FOV from 40° to 50°, that might not sound like a lot, but difference is big when you put it over your eye. Its easyer to walk with lens because it expands the FOV. I use this for airsoft, and this lense not only expands the FOV, but also protects the inner lense from BB impact, and that is a huge bonus! Lense is easy to mout, you just slide it on the NVG 30 or 50 default lense, it also comes with a protective cap so you avoid scraching the lense or dust getting in when you are not using it. However it adds weight to NVG a lot, and it adds to its size, so going trought doors with lens on and NVG rised up can be tricky. Lense has same dimensions as real analog PVS14 monocular, so you can slide lens on it aswell. All together good and usefull attachment for NVG 50 and 30.