Carlson's Choke Tubes Stoeger M3000/3500 Magazine Extensions - 10 Shot Black 10rd. These magazine extensions are constructed of blued solid steel and come with spring base clamp with swivel stud (included) to work with quick detachable swivel (not included). The threaded tube replaces you magazine cap and gives you the ability to add extra rounds to you magazine. Easy to follow instructions are included. The magazine extension tube is great for home protection competition shooting and law enforcement. See chart below for the make/model and the magazine capacity. Overall Length of Extensions: 04500 (8.25-inch) 04501 (10.5-inch) 04502 (6.25-inch) 04503 (6.375-inch) 04504 (14.25-inch) 04505 (8.25-inch) 04506 (6.25-inch) 04507 (8.25-inch) 04508 (5-inch) 04510 (13.88) and 04511 (8.5-inch) 04512 (8.38-inch) 04513 (8.13-inch) 04514 (14.13-inch) 04515 (8.13-inch) 04516 (14.13-inch) 04517 (8.5-inch) 04518 (14.25-inch) Magazine round count is for the total capacity using 2 3/4-inch shells including 1 in the chamber when using 3" shells you lose 1 shell capacity. When using 3 1/2" shells you lose 2 shell capacity. Example: 8 shot extension= is 7 (2.75" shells) in the extension and 1 in the chamber 6 (3" shells) in the extension and 1 in the chamber or 5 (3 1/2" shells) in the extension and one in the chamber. Remington extensions require removal of tabs / detent in magazine tube on newer model shotguns All extensions are 12 gauge only. Specifications for Carlson's Choke Tubes Stoeger M3000/3500 Magazine Extension: Manufacturer: Carlson's Choke Tubes Color: Black Condition: New Country of Origin: USA Features of Carlson's Choke Tubes Stoeger M3000/3500 Magazine Extension Stoeger M3000/3500 Magazine Extension 8 Shot Package Contents: Carlson's Choke Tubes Stoeger M3000/3500 Magazine Extension spring & barrel clamp Carlson's Choke Tubes 04514-10rd: Stoeger M3000/3500 Magazine Extensions - 10 Shot Black