Vortex Optics - Vortex Viper 6.5-20x50 rifle scope is ideal for tactical, long range, predator/varmint, and target applications. Side knob parallax adjust allows quick and easy parallax adjustments with range numbers visible while in the shooting position. 30mm main tube offers improved windage and elevation adjustment along with greater strength. Tall capped turrets allow quick and easy field adjustments. Dead-Hold BDC reticle has a customized design that helps eliminate guesswork on hold-over and windage corrections. Good for any hunting or shooting at varying ranges where estimating hold-over would be a concern.