Fortis Manufacturing, Inc. SLS Fifty, Safety Selector, Flat Dark Earth, Matte SLS-50-FDE When designing the new Fortis Super Lean Sport (SLS) FIFTY" Fortis made sure their brand's innovation" intent and quality were evident in every aspect of the design. While most AR safety selectors in the market today rely on standard socket/torx screws" the Fortis SS FIFTY was engineered with their patent pending RidgeKey locking mechanism. This system allows the levers to secure itself onto the selector core with a solid point of contact and thus eliminating any weak points in the system. The selector core is coated in black nitride" giving you a smoother surface and superior resistance to wear.