Nice that it takes a standard aaa battery - SIG SAUER OPMOD Romeo5X 1x20mm 2 MOA Dot Compact Reflex Red Dot Sight

This optics has a 2 MOA red dot. I prefer something that has selectable reticles, but I was interested in this because it takes a standard and widely available AAA battery. The optic isn't anything too fancy or exciting, BUT it works just fine. The 20mm lens is kind of small by today's standards. There are so many red dot optics similar to this one that I think the decision just boils down to your preference in batteries and AAAs are cheap and widely available.