The GrovTec US Mtmx3 is an extended magazine tube mount which is made specifically for the Remington 870 pump-action shotgun. It gives users 3 different methods for mounting their shotgun accessories, such as a sling. The components which come with this product include a Picatinny rail, swivel stud and push button base. The mount is compatible with the factory 12-gauge extended magazine tube of the Remington 870 and provides it with additional security. Not compatible with other magazine extensions like Nordic Components.