The 6378RDS holster is specifically designed for firearms with red dot sights. The holster features the ALS which locks the firearm securely in place when holstered but still allows a natural draw with a swipe of the thumb release as you establish your grip. SafariLaminate construction makes the holster strong on the outside, while SafariSuede on the inside protects your firearm's front sight and finish. Safariland cannot guarantee that RDS holsters will be compatible with non-factory (Glock MOS, M&P CORE, etc.) mounted red dots. Numerous variables including depth of RDS into slide, use of dovetail, placement on slide, etc. can all affect the fit of the holster. This holster is not compatible with the Trijicon SRO optic.