Things I liked:Red and green dots that actually vary in size and brightness, a good, solid mount that stays put. So far, it has held "zero". Only needs one battery and two were supplied. Very good battery life. Things I would have changed:The rear lens cover obstructs the adjustment knob. Just rotate the cover out of the way. What others should know:I put one of these on a Ruger Airhawk and liked it. I bought another and put it on a Ruger MarkIII .22 firearm. It is a solid, reliable sight.