This NC STAR Tactical Green Dot sight is designed to be used in conjunction with a magnified scope. For example, if you have this sight mounted on top of your 4x magnified sight it makes it easier to hit targets that would be too close for your primary optic. The NC STAR Tactical Red Dot sight come with everything you would need to mount and zero the reticle, it also comes with a spare battery for when the first one runs out of juice. The automatic brightness feature senses the amount of ambient light hitting the sight and adjusts the brightness of the reticle accordingly. The size and weight of this sight also makes it perfect to be mounted on speed competition shooting pistols.