Does what it’s supposed to - Knight's Armament KAC Logo Aimpoint Micro Battery Cap Assembly

I’ve had several of these they all work fine when you use 2 batteries like you are supposed to. It’s designed to hold a backup for your T-1/2 it also gives extra grip to turn your sight on. People tend to buy these , don’t put the spare battery in and then complain about their sight not working anymore. (One battery will pop loose under recoil) is it really needed on a T-1/2? Do you need to carry an extra pair of underwear? It’s one of these things that only you can answer but in the great words of Bert Gummer... “ When you need it and don't have it you sing a different tune”