Choate Tool Weatherby 459-8 Shot Magazine Extension 20Ga Matte12 Gauge. Will not fit the Semi Auto shotguns. Fits guns with barrels of 18 1/2 inches or longer. will add 2 rounds of 2 3/4 shells to your shotgun. These kits are constructed of solid blued steel and come with 1 Magazine Extension and a barrel clamp for mounting a sling and adding support. DOES NOT COME WITH NEW SPRING YOU USE THE ORIGINAL FACTORY SPRING Specifications for Choate Tool Weatherby 459-8 Shot Magazine Extension 20Ga Matte: Manufacturer: Choate Tool Magazine Capacity: 8 Round Gun Make: Weatherby Country of Origin: USA Features of: Adds +2 shotshells Machined from steel Includes clamp Package Contents: Choate Tool Weatherby 459-8 Shot Magazine Extension 20Ga Matte Choate Tool CMT-05-04-13: Weatherby 459-8 Shot Magazine Extension 20Ga Matte12 Gauge