The GUARDIAN is the strongest optic mounting system on the market. TRU-SEAL eliminates the need for an added sealing plate. 0-rings on the mounting screws hold the plate watertight to the slide, sealing out moisture, eliminating corrosion in the mounting threads. Radian's 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.