The STI Recoilmaster is a complete kit that produces significant reductions in muzzle climb and recoil. This gives the shooter more consistent performance and brings the gun back to point of aim more quickly than convention recoil assemblies. Light Recoilmaster is for 9mm Luger and 38 Super, while the Heavy is for 40 S&W, 10mm Auto and 45 ACP. Both include a takedown tool. Requires installation by a qualified gunsmith.
Open Class guns and all 9mm use the Light system. Guns, other than 9mm guns, with "tight" slide fit, and guns with unmodified or classic slides use the Heavy system.