Mossberg 12 Gauge X-Factor Accu-Mag Improved Cylinder Extended Ported Waterfowl Choke Tube. Fits Mossberg 935 Magnum, 835 Ulti-Mag, SSi-ONE Turkey, and Maverick 91 Accu-Mag Choke 12 Gauge Models Only. Specifically angled ports to reduce perceived recoil. Designed to handle most lead, steel, and other non-toxic loads. Not for use with slugs.