The Primary Arms 4-16x Second Focal Plane Scope features an illuminated Mil-Dot reticle for ranging targets at 16x magnification. The second focal plane design keeps the reticle the same size at all magnifications. Locking turrets with re-settable zero give audible and tactile 1/4 MOA clicks. A side mounted parallax adjustment knob keeps the reticle parallax-free and the target image sharp at extended ranges. The partial red illumination of the reticle is powered by the included CR2032 battery and has a total of 12 brightness settings. This tough scope is shockproof, waterproof and fog resistant.