This Optics Mount Plate is designed to connect Optics Red Dot Reflex Sight to Ruger Security 9 full size and compact size pistols by Replacing the Rear Sight with this Optic Mounting Plate. This plate fits Vortex Viper, Vortex Venom, ADE RD3-003, ADE RD3-006, ADE RD3-009, ADE RD3-012(and Pro), RD3-015(and Pro), RD3-028, ADE RD3-018 Spike, , Docter/Noblex Sight C, Docter/Noblex sight 2+, Docter/Noblex sight III, Docter/Noblex QUICKsight 5.0 VR, Noblex Sight G,Burris Fastfire 2, 3, Delta Optical MiniDot, Delta Optical MiniDot II, Hawke Reflex 1×25, Sightmark Mini Shot Pro Spec, Sightmark Mini Shot M-Spec, Leica Tempus, MAKdot 1×25, Vector Optics SCRD-19II Frenzy 1x17x24, Creative XP GlassEagle HD, HEX Dragonfly, Crimson Trace CT RAD Pro, Cyelee CALF V2, or Vomz Pilad 1×20. Also fits Burris Fastfire 2, Burris Fastfire 3, Delta Optical MiniDot, Delta Optical MiniDot II, Hawke Reflex 1×25, Sightmark Mini Shot Pro Spec, Sightmark Mini Shot M-Spec, Leica Tempus, MAKdot 1×25, Vector Optics SCRD-19II Frenzy 1x17x24, Creative XP GlassEagle HD, Riton MPR D2, Riton 3 Tactix MPRD, Swampfox Sentinal, HEX Dragonfly, HEX Wasp, Crimson Trace CT RAD Pro, Cyelee CALF V2, Cyelee CAT PRO, or Vomz Pilad 1×20.