Elcan Specterdr 1/4x 5.56 NATO Flat Dark Earth by Elcan Hard-anodized aluminum in Flat Dark Earth;Fits any Mil-Std-1913 Picatinny Rail;Dual-thickness ballistic crosshair with user-selectable red dot, VSOR rangefinder, and area fire circles.;Battery-powered LED Illumination, Battery Life: 600 hours minimum, 3000 hours average Flat Dark Earth