This red dot uses the Shield RMSc footprint standard. Essential info Footprint standard: Shield RMSc footprint standard Reticle: 2 MOA dot & 32 MOA circle [red] Window size [height x width]: 14.0 x 21.0 mm [0.55 x 0.83"] Total dimensions [length x width x height]: 40.5 x 25.0 x 24.5 mm [1.59 x 0.98 x 0.96"] This red dot uses the Shield RMSc footprint standard. Key Features Enclosed Emitter Optic: Fully sealed design for superior protection and reliable performance in any environment. Aspherical Lens: Zero distortion and parallax-free clarity through a large window for fast, precise target acquisition. Side Load Battery: Easy CR1620 battery replacement without removing the optic, preventing the need for re-zeroing. RMSc Footprint: Directly fits optics-ready slides, offering broad compatibility for seamless integration. 2 MOA Dot & 32 MOA Circle: Choose between dot-and-circle, dot-only, or circle-only reticles for any shooting scenario with a sharp, bright aiming solution.