All-steel extension tubes attach directly to the end of the magazine tube and increase capacity by as much as five rounds. Extension cap is machined from solid steel and welded to seamless steel tubing for extra strength. Includes extended magazine spring. Barrel Magazine Clamp (BMC) - Clamps to the barrel and the extended mag tube and is available separately for all other models.
SPECS:
Steel, blue, matte finish. 12 ga. only. Rounds (RDS) indicates number of rounds extension adds to factory magazine capacity model.
Catalog page 191