The Cross Armory Rear Sight Dovetail RMSc Mount Adapter replaces your factory rear dovetail and provides a low-profile RMSc mounting platform plus a bright green fiber-optic co-witness front sight all in a single, precision-machined 17-4 stainless steel unit with a durable black nitride finish. Optic not included. Compatible Glock models (OEM dovetail, non-MOS): 17, 19, 19X, 20, 21, 22, 23, 24, 26, 27, 29, 30, 30SF, 34, 36, 42, 43, 43X, 45, 48. *Does NOT fit Glock 44.