Dophee Tactical QD Quick Detach Quick Release Swivel Sling Mount fits 20mm Weaver Rails Rail Mount: 20 mm. Material: Aircraft grade aluminum and steel. Metal Ring Diameter: 0.18" Metal Internal Width (Max): 1.25" Cylinder External Diameter (Max): 0.6". Fit on 20mm weaver rails. Compatible with Large 1-1/4" push button sling loop.