Elzetta ZSM-T Flashlight Mount for Tactical Shotgun, Remington 870, Mossberg 500, Quick Release Thumbscrew Model Fits Remington 870, Mossberg 500 and 590, Benelli M4 and Others Requires 1.75 Inches of Free Space on the Magazine Tube and Barrel Sizing Adapters Accommodate Flashlights From 0.70" to 1.05" in Diameter Quick Release Thumbscrew Allows Rapid Installation and Removal of Flashlight Attaches to Either Side of Shotgun