The Battle Arms Pro Ambidextrous Select Fire Safety Selector Lever is the perfect upgrade to your AR-15/M4/M16 Machine-gun. The standard and short safety levers are fully interchangeable and modular to accommodate left or right-handed shooters. The BAD-ASS-PRO-FA is now 100% compatible with all known AR variant lower receivers, and triggers designed to work with the "Mil-Spec" AR-15/M4/M16 full-auto safeties. No longer do you have to choose which trigger is compatible with the safety! If the trigger it will work with a "Mil-Spec" AR-15/M4/M16 full-auto safety, it will work with the BAD-ASS-PRO-FA!No more broken screws! Don't settle for wiggling levers! No more stripped screw heads! The patent-pending dovetail design and internal locking mechanism make it impossible to shear off the screw head because there is no screw head! Do not settle for spring-loaded detents that never give your safety lever that positive lock of confidence and worry about losing t...