Lancer shotgun extension tube mossberg 590/930 plus4 FEATURES-Adds 4 rounds to capacity-Length: 10.3"-Designed to attach to existing shotgun magazine tubes to provide added capacity to the shotgun-Machined aluminum components combined with a lightweight carbon-fiber tube-Creates a lightweight, durable extension to your shotgun-An extra-long spring is included that can be cut to optimize loading-Extension clamps are recommended for extension tubes that extend beyond the end of the barrel Other Features: Extra long spring included that needs cut to length, plus 4 rounds, length 10.3"