Safariland 6304 ALS Tactical Leg Holster, Black, STX, Glock 20, 21 ALS (Automatic Locking System) secures weapon once Holstered. Low-Ride level Simple Straight up Draw after deactivating the release Standard double strap leg shroud with mounting holes for optional accessories Safari laminate Thermal Molded construction protects the handgun and sights (ALS ) Automatic Locking System secures weapon once holstered (includes SLS hood assembly and Hood Guard) Adjustable vertical leg strap, standard double leg strap and leg shroud with mounting holes for optional accessories Simple straight up draw once all releases are de-activated Mounted to the same leg shroud assembly as the popular 6004 series Thermal-molded SafariLaminate construction protects handgun and sights