The Ruger Optic Adapter Plate supports the use of Docter(R), Meopta, EOTech(R), Insight(R), Noblex(R) red dot sights on the Ruger-57 pistol. Also fits the TruGlo(R) Tru-Tec? Micro TG8100B. The plate is precision CNC machined from 6061-T6 aircraft aluminum with a matte black hardcoat finish for strength and durability. 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(R) T-15 wrench (not included). Install the optic onto the Adapter Plate by following the sight manufacturer's mounting specifications (sight not included). The Adapter Plate is 1.700" long x .975" wide and weighs .2 ounces. This Genuine Ruger Factory Accessory is made in the USA.