Great for the price. - SightMark SM26010 Ultra Shot M-Spec FMS Reflex Sight

Looked at a lot of reviews and saw mixed answers on some specifics I was looking good for. First was that, the battery is a CR2. Some say a CR123, some say CR2. The FMS has a motion sensor so you can keep it "on" all the time. That's the main reason I got it. And it works great. What is not clear is that the "quick detach one also has the motion sensor. At least that's what the instructions say. If I had known I probably would have gotten the quick release instead. Other than that, It works great.