Grovtec mtmx3 extended mag 12 tube mount mossberg/rem 1100 FEATURES-For Mossberg 500, 835, 590, 930, 935 & Remington 1100, 12 gauge-Provides three different ways to mount your sling or accessories:-Picatinny rail -Push-button base -Standard locking swivel stud-The steel magazine tube mount gives extra security to the 12 gauge extended magazine tube-Rail & push button base are reversible & can be mounted to either side Other Features: 3 dif ways to mount slings or access; picatinny rail,push button base & locking swivel stud....Reversible