Read the instructions! - BSA Optics Sight System w/ Multi Purpose Reticle

Great little sight. Mine broke when one of my idiot friends dropped my rifle on concrete when it was still attached. I would recommend this item and others like it over tube-style red dot sights. There is less vertical "stringing" of shots with reflex sights as opposed to red-dot sights because there is less movement of the sight picture and more reference points.
Pros: Good price, accuracy, sight picture and battery life.
Cons: Should use thumb screws instead of alen-wrench screws.

This review was written in the old system and had content requirements that are different than reviews written today.