Vortex Crossfire II 4-12x50 Dead-Hold AO Rifle Scope features a long eye relief, a quick focus eyepiece, fully multi-coated optics with resettable MOA turrets. This rifle scope is robust and while viewing, it remains crisp clear with an emphasized brightness. Vortex Crossfire II 4-12x50 Dead-Hold AO Rifle Scope framework is a single-piece hard anodized finish of airplane-grade aluminum tube that is nitrogen purged, and O-ring sealed to address for water and fogproof performance. a Dead-Hold BDC Reticle a 1" Maintube Diameter a Fast Focus Eyepiece a Nitrogen Purged Interior a Capped/Resettable W/E Turrets a One-Piece Aerospace Aluminum Housing a Waterproof/Fogproof/Shockproof