12 Gauge model X-Factor chokes for use with Mossberg 835 and 935 threaded barrels. 20 Gauge models for use with Mossberg 500, 505, 510 Mini, and Maverick 88 threaded barrels. Also compatible with Smith & Wesson, Savage, & U.S. Repeating Arms (Win-choke) and Browning Invector interchangeable choke models.