This holster features the Automatic Locking System (ALS®). 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. Additional retention is achieved when used with the SLS rotating hood. This holster has the QLS 19 Locking Fork installed. The QLS 19 Locking Fork can be used with any mounting platform (leg shroud, belt loop, etc.) that has the QLS 22 Receiver Plate installed. ** 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.