Universal picatinny rail mount for most drilled and tapped shotgun models: Mossberg 500/590/835/930/Shockwave, Remington 870 Express Tactical, Winchester SXP Defender/1300, Benelli M1/M2/M3, Super Black Eagle I/II, Stoeger M3000/M3500, Remington 7400/7600, Franchi Affinity 3/3.5, Weaver 93 pattern, plus many 22lr and short action rifles (Ruger 10/22, Marlin 336/1894/1895, Henry Big Boy). Mounts rings, red dots, or optics using Picatinny 1913 or Weaver standard. Rail is 4.5 inches (11 picatinny slots).