Some people say they are crap, without really saying why. I like them. Good value. I use Mamba Lite on air rifles (pcp and spiringers), rimmys and 243. Viper on 223 and 308. I can see bullet holes in target at 200yds. White part only, cant see them in black. So far not lost zero on any of them.
They are good for IR night vision, apparently the lens coatings on some of the better scopes is so good it absorbs too much IR.
I don't worry to much if they make contact with the high seat when you are pulling the rifle up on the end of a rope.