The Binary(R) Firing System(R) GEN 3 (BFSIII(R)) is a 3-position trigger. In position 3, it fires one round on pull and one round on release. This trigger is ideal for having more fun than you thought was possible with your Ruger(R) PC Charger(TM) and Ruger(R) PC Carbine(TM). TRIGGER OPERATION: Position 1 - Safe -Will not fire Position 2 - Semi - Fires 1 round per pull Position 3 - Binary - Fires 1 round on pull and 1 round on release FEATURES: * Release round can be canceled by simply moving our Patented selector out of Binary(R) mode while holding the trigger back * Works in most 9mm and .40 Cal Ruger(R) PC Carbine(TM) trigger housings * Great for competition shooters, tactical shooters, and recreational enthusiasts * Gunsmith Installation Recommended