NcSTAR NC Star SMAG3XRB24, 3X Magnifier with RB24 30mm Ring Prismatic lens for a clear high definition image quality Fully adjustable for elevation and windage, to get your primary optics reticle centered in magnifier Quick focus ring to get your primary optics reticle in focus Prismatic lens for a clear high definition image quality Fully Adjustable for Elevation and Windage Quick Focus Ring to get your Primary optic's reticle in focus RB24 places the center of the 3X Magnifier at 11/2" above the rail, a popular AR15 Optics height 30mm Magnifier body diameter, for compatibility with other mounting options