Matte Black Anodized 6061-T6 Aluminum Construction. 3.94″ Scalloped 9 Slot Picatinny Rail with 0.59″ Saddle Height. Compatible with Most 9mm – 11mm Flat or Round Dovetail Rails. Full Length Locking Side Plate for a Secure and Repeatable Zero Hold. Optional Recoil Stop Pin Provides Additional Retention Against Bidirectional Recoil