PRODUCT FEATURES Heavy Duty, 25.4mm/1'&'; and 30mm Diameter, 19mm 0.75in Center Height Low Profile 4 Torx Screws Per Ring, Accurate w/ CNC Machined, Solid Steel Construction Fit On 21mm Picatinny and Weaver Rails X-Accu Steel Scope Rings Item Quickly Mount Model Profile Height(from bottom to ring center) Ring Width Weight 25.4mm 1" Steel Weaver Rings Without Quick Release Mount XASR-S01 Low 19mm / 0.75in 18mm / 0.7in 152g / 5.4oz XASR-S02 Medium 25.4mm / 1in 198g / 7.0oz XASR-S03 High 32mm / 1.25in 245g / 8.6oz Quick Release Mount XASR-SQ01 Low 19mm / 0.75in 165g / 5.8oz XASR-SQ02 Medium 25.4mm / 1.0in 165g / 5.8oz XASR-SQ03 High 31.8mm / 1.25in 165g / 5.8oz 30mm Steel Weaver Rings Without Quick Release Mount XASR-S11 Low 25.4mm / 1.0in 199g / 7.0oz XASR-S12 Medium 31.8mm / 1.25in 267g / 9.4 XASR-S13 High 38.1mm / 1.5in 300g / 10.6oz Quick Release Mount XASR-SQ11 Low 25.4mm / 1in 214g / 7.5oz XASR-SQ12 Medium 32mm / 1.25in 261g / 9.2oz XASR-SQ13 High 38.1mm / 1.5in 316g / 11.1oz Quick Release Scope Rings Without Quick Release Scope Rings