Some models of Benelli shotguns are being shipped with no magazine extension. Instead, these models have a cap that screws onto your magazine tube. This cap holds the barrel/forend assembly firmly against the receiver.
The DMW extension nut works as a coupler, allowing you to install either a factory or DMW extension tube in place of the cap. The extension tube nut holds all components firmly in place, as the factory cap does, but adds greatly to the versatility of your weapon. Made from aircraft quality aluminum, hard anodized in matte black to match the finish of your weapon. Proudly Made in the USA by Dave’s Metal Works