Shield Sights Low Profile Slide Mount for Glock 21 Black. Compatible with the SHIELD footprint. Specifications for Shield Sights Low Profile Slide Mount for Glock: Manufacturer: Shield Sights Red Dot Sights-Footprint: SMS Optic Cut: Not Applicable Color: Black Gun Make: Glock Gun Type: Pistol Package Contents: Shield Sights Glock 21 Low Pofile Slide Mount What firearm models does the manufacturer say Shield Sights Low Profile Slide Mount for Glock is compatible with? The manufacturer suggests that Shield Sights Low Profile Slide Mount for Glock is compatible with Glock 21 Glock 19 Glock 17 Glock 22 Glock 43Shield Sights MNT-G21-POLY-SMS/RMS: Low Profile Slide Mount for Glock 21 Black