Originally Posted by bentbiker
If you are talking about the RM02 in Genin's pictures, you don't do anything to activate it. As for the batteries dying, if you have backup iron sights, what would be the concern?
Edit: I was too slow. Genin answered.
My concern would be the time it took to transition your brain and eyes from expecting a red dot, not getting one in the moment of truth, to acquiring iron. I suppose I need to play with one to determine what this would be like.