The Ruger-57 Optic Adapter Plate supports the use of JPoint MRD. & 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 in-lbs.) 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. The Adapter Plate is 1.700 long x .975 wide and weighs 0.02 ounces.