Anyone ever use a sight set like these? Someone was describing them to me, and from what I gathered, a lens goes on the other side of your pins (you can get 2x or 4x) and it magnify's the target and leaves your pins the same size.

First, does anyone know anything about these? Secondly, anyone ever use them? And most importantly, can anyone link me to where I can buy one, lol.

Thanks.