Vortex Viper HD 5-25x50 Rifle Scope, 30mm Tube, First Focal Plane SPECIFICATION : Manufacturer: Vortex Objective Lens Diameter: 50 mm Magnification: 5 - 25 x Tube Diameter: 30 mm Reticle Focal Plane: First Focal Plane (FFP) Field of View, Linear: 23.6 - 4.7 ft at 100 yds Eye Reli..