The Nightforce ATACR 4-20x50mm F1 fills an important magnification range in the ATACR line. Equally at home atop a bolt action or a semi-automatic rifle, the 4-20x50 F1 is smaller and lighter than the 5-25x56 F1 while offering a 25% improvement in magnification over the 4-16x42 F1. With Digillum, a ZeroStop turret, power throw lever, ED lenses, and 20x max magnification, the ATACR 4-20x50 F1 is their apex mid-power scope. If there is such a thing as a "professional" riflescope, it is an ATACR(TM). They are designed for military, law enforcement, hunters, and other tactical professionalsa | and for those who simply want to shoot like a professional. An ATACR& Mfg: Nightforce