Winenton choke tubes are precision-machined to high tolerance standards using computer-controlled equipment. We use 4140 grade steel to manufacture top-quality shotgun chokes. Winenton extended choke tubes are compatible with many Ber/Ben 12 ga shotguns, also fit shotguns included Italian, American, Turkish etc. shotguns that use Ber/Ben 12 gauge Mobil Choke thread. Please make sure or contact us if the choke tubes fit your shotgun. Use Full Choke (F) for targets at 40+ yards or further. ( Use only LEAD! ) Use Improved Modified Choke (IM) for targets up to 40 yards. ( Use only LEAD! ) Use Modified Choke (M) for targets up to 35 yards. ( Use only LEAD! ) Use Improved Cylinder (IC) for targets up to 30 yards. ( Use LEAD & STEEL! ) Use Cylinder Choke (C) for targets less than 25 yards. ( Use LEAD & STEEL! ) 12 ga Extended Shotgun Choke Tube Set come with; 5x extended choke tubes ( F - IM - M - IC - C ), Polymer bag and Choke tube wrench. Choke Tube Diameters F: .685 IM: .695 M: .705 IC: .715 C: .723 You can contact us at any time through Amazon messages if you have any questions, comments or product requests. We will respond to you within 24 hours and do our best to help you out. We encourage our customers to contact us with any questions or concerns. We'd like to be sure you are completely satisfied with your purchase.