Vortex Viper 6.5-20x50 PA Riflescopes are necessary when precision shooting at high magnification is a must. The unique ViewMag adjustment lever of these riflescopes by vortex allows you to make rapid power adjustments without ever taking your eye off your target. Vortex Viper 6.5-20x50 PA Waterproof Scopes have pop-up dials which provide easy, precise adjustment of elevation and windage, making audible clicks easily and quickly counted. The Vortex Viper 6.5-20x 50mm PA Matte Side Parallax Scope consists of a rugged, durable 30mm tube constructed of 6061 T6 aircraft-grade aluminum. Vortex subjects all of their riflescopes to demanding factory testing under a force of 1000 G's - 500 times! Not only is this rifle scope waterproof, fogproof and shockproof, it is highly prized for its purging with Argon gas, targeting corrosion in an unchallenged way. This feature helps to eliminate internal fogging, chemically ignoring water. Like the Diamondback riflescopes, you can count on the Vortex Viper 6.5-20x50 PA Matte Riflescope w/ V-Plex Wide Reticle for smooth handling when the heat is on.