Volquartsen Firearms VC Mainspring for Ruger MKII and MKIII Black. Mainspring components are wire EDM-cut and CNC-machined. Our mainspring does not feature the lock feature found on the Ruger factory MKIII Mainspring. Included Accessories: - Models available for either the Ruger MKII/MKIII or the 22/45 Specifications for Volquartsen Firearms VC Mainspring for Ruger Pistols: Manufacturer: Volquartsen Firearms Color: Black Finish: Matte Gun Make: Ruger Condition: New Country of Origin: USA Package Contents: Volquartsen Firearms VC Mainspring for Ruger Pistols 22/45 What firearm models does the manufacturer say Volquartsen Firearms VC Mainspring for Ruger Pistols is compatible with? The manufacturer suggests that Volquartsen Firearms VC Mainspring for Ruger Pistols is compatible with Ruger Mark II Ruger Mark III Ruger 22/45Volquartsen Firearms VC3MSR-3-B: VC Mainspring for Ruger MKII and MKIII Black