On my SBE, I've got one of the earlier generation Aimpoints in 1997 or 98 that resembles later generations, but isn't. The next generation after mine claim 50,000 hours. The cost of a battery is negligible and I changed out yearly to be on the safe side. I haven't used the gun in three seasons as I now use Trijicon Reflex sights on my 20 gauge guns that have tritium lamps--no need for batteries.