One comment on the brightness setting for those that have never used one before. The brighter the ambient light, the brighter you need to have your red dot so you can see it. On the Aimpoint, I find that the brightest setting is too much even out in the desert during the summer. The problem with having the brightness set too high is that the dot starts to blur, or put another way, the dot doesn't appear to be nice and round and crisp. This makes real accurate shooting more difficult. Now if you were expecting to be making extremly fast, close shots this doesn't matter and having the dot brighter will make seeing it all the easier. But, most of my shooting is done two settings below the max. This gives me a dot that is still easy to see and easy to pick up, yet it is nice and round so you can make more precise shots. If I am shooting on paper, I set the sight for the lowest setting that still allows me to see the dot. The result is that the worst case senario battery life numbers are almost never needed since the sight on my rifle is basically never on the highest setting. At night, I use maybe the second or third lowest setting and it is plenty bright enough. Lastly, the batteries arn't expensive, so if I am doing something like taking a carbine class, I just put a new battery in even though the present battery would probably last for weeks on the brightest setting; but, for a couple bucks, why not just be sure ? I have never had a battery wear out in a dot sight. I have an older Aimpoint sight on a Ruger MKII that has been in the sight for years and I bought the gun used, so who knows how long it has been in that sight ? Put in very simple terms, the batteries are not an issue. I wouldn't be surprised if a GI joined the military on a four year hitch and could have the same battery in the sight when he is discharged.