Manufactured from 1704 heat-treated stainless steel. These chokes may be used with lead shot on any constrictions. Steel shot larger than #BB should not be used in any choke tighter than full.Specifications:- Gauge: 12- Type: Flush Mount- Choke: Improved Cylinder- Constriction: .720(This Product does not fit the Remington Pro Bore or the Remington Spartan Models)