Volquartsen Firearms Safety Pistol Power Spring Ruger MK IV 22/45. " The increased force addresses those shooters who may inadvertently engage the safety during firing. Specifications for Volquartsen Firearms Safety Pistol Power Spring Ruger MK IV: Manufacturer: Volquartsen Firearms Gun Model: Ruger Mark IV Ruger Mark IV 22/45 Country of Origin: USA Features of Volquartsen Firearms Safety Pistol Power Spring Ruger MK IV Fits Ruger MK IV MK IV 22/45 and MK IV 22/45 Lite Package Contents: Volquartsen Firearms Safety Pistol Power Spring Ruger MK IV What firearm models does the manufacturer say Volquartsen Firearms Safety Pistol Power Spring Ruger MK IV is compatible with? The manufacturer says that Volquartsen Firearms Safety Pistol Power Spring Ruger MK IV is compatible with Ruger Mark IV Ruger Mark IV 22/45Volquartsen Firearms VC4SPS: Safety Pistol Power Spring Ruger MK IV 22/45