its a perk in FNV it give you Low-Light Vision and its pretty much useless since you can just adjust your gamma to see in the dark also when taking the perk and the Low-Light Vision you cant remove it so yeah its USELESS
It never really gets that dark, and there's always Cateye. Also, it only works at night, so if you go into a cave or dark ruin during the day you won't get the effect. Use your perk choice on something better.
not worth it between cateye, nuka cola quartz, and dead money's ghost sight which are mostly easy to get.. so its a waste of a perk