The 6390RDSO holsters are designed for firearms with red dot sights. Its Automatic Locking System (ALS) secures the firearm. Unlike Safariland's RDS series, the RDSO has an open pocket that protects the optic and does not use a flip-up dust cover. Features a mid-ride belt loop that is rides close to the body.Safariland cannot guarantee that RDS holsters will be compatible with non-factory (Glock MOS, M&P CORE, etc.) mounted red dots. Numerous variables, including placement of the RDS on the slide, use of dovetails, can affect the fit. FeaturesALS (Automatic Locking Systems) secures weapon once holstered; simple straight up draw once release is deactivatedFor use with red dot optic-equipped weaponsSafariLaminate thermal-molded construction protects handgun and sightsSuede lined to protect handgun's finish