This kit alloows the ROMEOZero optic to be mounted to a Springfield Armory Hellcat OSP or Glock G43X MOS pistol. If mounting the optic with the included protective steel shroud, use the longer M4x0.7x10.04 Screws (Part # 7403049). If not, use the shorter M4x0.7x9.04 screws (Part # 7403032) Torque the screws to 9 in-lbs.