MTMx3 Ext. Magazine Tube Mount X3 Rem 870 Description Provides three different ways to mount your sling or accessories; a picatinny rail a push button base and a standard locking swivel stud. The steel magazine tube mount gives extra security to the 12 gauge extended magazine tube. Rail and push button base are reversible and can be mounted to either side. Specifications: Fits: Remington 870 12 Gauge Color: Black Made in the USA