Night vision can get expensive and if you're doing it on a budget, saving $80 here, $100 there, etc. can really add up to either save you a good amount of money overall or allow for a larger budget when purchasing other accessories.
You can always just pull your charging handle and slide this thing on from the back of the gun. If you run a BUIS, use a torque wrench for consistent torque which will increase the chance of a repeatable zero if you have to remove and remount it. Personally, I'm finding that less and less of my guns seem to need BUIS, especially for NV rigs, because in my experience it's pretty hard to use BUIS in night vision shooting conditions.
If money isn't an issue, the Unity Aimpoint Micro mount with an ADM QD lever added to it is an awesome setup.