The Radian GUARDIAN Optic Guard provides unprecedented protection for your pistol red dot optic. Machined from 7075 aluminum and hard anodized, the design provides top/front/side impact protection. STUD-LOK threaded stud/nut mounting interface is a secure system. It provides much longer thread engagement, greater hold down power, with increased shear resistance. TRU-SEAL eliminates the need for an added sealing plate. Pre-installed O-rings on the mounting screws hold the plate watertight to the slide, sealing out moisture, eliminating corrosion in the mounting threads.