Poor battery life and mine doesn't pulsate. - LaserMax Uni-Max Picatinny Rail Mounted Lasersight, Green

I have this unit and mine doesn't pulsate as noted in the description. Mine only stays constant on which I prefer but would like the unit to have a monetary on off switch. I have replaced the batteries several times and the batteries I believe loose the brightness of the laser beam even though the unit is shut off. With fresh batteries the green laser beam is only bright for about three minutes if left on. It could be that the batteries would last longer if they were removed from the unit but that would be ridiculous. I for one also have the Veridian Green Laser Rail unit and it is much brighter and the C123 Batteries are much more powerful and for sure last much longer.