The m17 and m18 pistols have been selected by the us military as the official sidearm and the romeo-m17 is the only optic that is truly designed specifically for this pistol.All other optics have many disadvantages and make several compromises.The romeo-m17 does not.This is an american-built mil-spec red dot truly worthy of the sig sauer name.*please note - the romeo-m17 pistol red dot sight utilizes sig sauer's proprietary sig-loc mounting interface and only fits sig sauer m17/m18 military issue and commemorative pistols with a single optics plate mounting screw.This sight will not fit any other pistols.Battery Size: CR2032Magnification: 1xObjective: 24 mmDot Size: 2 MOA/32 MOALength: 2.40"Weight: 1.50 ozReticle: 2 MOA Red Dot/32 MOA Circle Multi ReticleAdjustment Size: 1.5 MOAProofs: WaterproofWindage Elevation: Adjustable