Same Sig Sauer Romeo-RS enclosed-emitter pistol red dot as the 3 MOA version, but with a larger 6 MOA dot for faster close-range acquisition. Compact footprint for slim subcompacts. Specs: Reticle: 6 MOA red dot Housing: aluminum, matte black, fully sealed enclosed emitter Illumination: motion-activated, multi-brightness Battery: top-loading Footprint: Compact / Shield RMSc - fits Sig P365 / Glock 43X-48 / S&W Shield Plus cuts 6 vs 3 MOA on a subcompact carry pistol: 6 MOA is generally the better choice for self-defense use - slim subcompacts are short-range tools, and the bigger dot is faster to find. Choose 3 MOA only if you regularly shoot precision drills at distance.