"Pro-Factor" Choke Tubes by Mossberg. Introducing the all-new PRO-FACTOR choke tubes, a massive lineup of precision-machined chokes, designed to fit the needs of just about every hunter or shooter, and covering many models and makes. With performance and value in mind, these chokes were developed for use with some of the most popular shotgun brands around. A wide variety of flush and extended ported tube configurations are offered, including Skeet, Improved Cylinder, Modified, Full, X-Full, and XX-Full constrictions. Features: - Model: PF1 - Choke size: Flush Improved Cylinder Specifications: - Gauge: 20 - Finish: Black - Fits: Mossberg Accu-Choke models, Maverick Accu-Choke models, Winchester 1300, Browning Invector models, H&R Excel, Ithaca, New England Firearms Pardner, Stoeger Uplander/Condor Models.