This Optic Adapter Plate is compatible with Sig Sauer ROMEOZero, JPoint MRD, and Shield RMS red dot sights on the Ruger-57 pistol. The plate is precision CNC machined from 6061-T6 aircraft aluminum with a matte black hard coat finish for strength and durability. Simply place the adapter plate onto slide and secure it using the two #6-32 screws provided. Tighten the screws firmly (30-50 inches-pounds) using a Torx T-15 wrench (not included). Install the optic onto the Adapter Plate by following the sight manufacturer's mounting specifications (sight not included). NOTE: the extra screws provided in the package are meant for installing the JPoint sight only. Shield sights should fit this base without modification. This plate does not fit Holosun 407K or 507K optics. The Adapter Plate is 1.700 inch long x .975 inch wide and weighs .2 ounces. This genuine Ruger factory accessory is made in the USA.