Compatibility Specifications These choke tubes are manufactured for the Mobil threading system. Compatible with 12-gauge shotguns utilizing the Italian/Turkish Mobil thread pattern. Not compatible with Optima, Crio, Invector, or Remington threading systems. Please verify that factory chokes are stamped with "Mobil" prior to installation. Installation Instructions 1. Ensure the firearm is unloaded and the barrel is pointed in a safe direction. 2. Remove the existing choke using a compatible wrench (included) by turning counter-clockwise. 3. Select the desired choke tube based on shooting distance and shot type. 4. Thread the new choke by hand until seated. 5. Use the wrench for final tightening until the tube is snug against the barrel shoulder. Choke Selection and Patterning Full (.685): Optimized for 40+ yards (Lead shot only). Improved Modified (.695): Optimized for up to 40 yards (Lead shot only). Modified (.705): Optimized for up to 35 yards (Lead shot only). Improved Cylinder (.715): Optimized for up to 30 yards (Safe for lead and steel). Cylinder (.723): Optimized for under 25 yards (Safe for lead and steel). Safety and Technical Data Material: Precision-machined 4140 high-tensile steel. Finish: Black oxide coating for corrosion resistance. Warning: Full, Improved Modified, and Modified chokes are restricted to lead shot only. Using steel shot in these constrictions may cause barrel damage. Improved Cylinder and Cylinder chokes are rated for both lead and steel shot.