even though the 4.5 is shorter than the 3x milspec, it wouldn't fit on my rail. I will have to move my Aimpoint one slot further out to use it which also means that there would be no room for the laser at 12 o'clock if I use the 4.5x anyway. since I would have to re-zero the Aimpoint when I move it, it may be a while before I bother with it. after wearing the helmet for about 30 minutes last night, I couldn't stand it on any longer. and I couldn't see well with it in the first place. it still feels like it's on my head...