The Sidewinder Conversion System is a unique accessory for your Mossberg 12 gauge shotgun. This kit allows you to use 6 or 10 round magazines without the need to permanently alter your shotgun. Simply remove the barrel, unscrew the factory magazine tube and install this custom tube. With the Sidewinder installed, you can instantly reload your shotgun by dropping the empty magazine and inserting a full one. Perfect for the 6-shot Mossberg 500, 590, 590A1 or Maverick 88. Use with the 590 will require the purchase of an adapter tube (sold separately). No gunsmithing or permanent modification of the shotgun is required.