The Radian Guardian Optics Guard is the strongest optic mounting system on the market. TRU-SEAL eliminates the need for an added sealing plate. O-rings on the mounting screws hold the plate watertight to the slide, sealing out moisture, eliminating corrosion in the mounting threads. Radian STUD-LOK threaded stud/nut mounting interface is the most secure system on the market. This provides much longer thread engagement, greater hold down power, with increased shear resistance.Includes(1) GUARDIAN Optic Mount and Guard Plate(2) Plate Mounting Screws(2) TRU-SEAL 0-Rings(2) STUD-LOK Studs(2) STUD-LOK Self-Locking Sleeve Nuts