They shut off after 4 or 8 hours depending on which button you push. I prefer the Aimpoint for battery life but it's not that hard to push a button before we put on our electronic ear pro, bullet proof vest and all...

I have one of the newer versions and it has zero battery drain like some of the older ones did and the reticle is a better fit for my bad eyes. This one has performed as good as any of my Aimpoints ever did except for leaving it always on but I'll trade the accuracy I can get out of the EOTech over the Aimpoint any day.