The 6360RDSO holster is specifically designed for firearms with red dot sights mounted to them. This holster with the Automatic Locking System (ALS®) builds on the foundation of the Self Locking System (SLS). It locks the weapon in all directions upon holstering, it's operable with the thumb, and the weapon can be drawn straight out of the holster with no twisting required. 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.