Manufactured from 17-4 stainless steel and hardened. For use with lead shot in all constrictions. Steel shot larger than #BB should not be used in any choke tighter than modified, BB and smaller size steel shot may be used through full choke constriction.Specifications:- Gauge: 12- Type: Flush Mount- Choke: Cylinder- Constriction: .730Interchangeable with Winchester, Mossberg, Browning Invector, Weatherby, and Savage 12 Gauge Shot Guns