2: yeap but so do pace makers, only with laser batteries, if they go you have your iron sights so they are worse off. Batterys on CT lasers are suppose to last 2 years. I shouldnt take 2 years to get on target. They are cheap, if thats a concern, change them every six monts.
I change mine out at the same time I check the batteries in my smoke alarms -- on the days we switch from daylight savings time and back again.