NcSTARs Shotgun Magazine Tube Rail Mount is design to fit onto most 1 diameter Extended Shotgun Magazines tubes. When mounted onto you Shotgun Extended Magazine tube, this will allow you to attach multiple weaver & Picatinny style accessories to your shotgun. The rails are designed so that you can attach your accessories like Lasers and Flashlight at any of the 5 angles that the rails provide. Not only can you mount your accessories at the typical 3, 6, and 9 Oclock positions you can also mount the accessories in the 4/5 and 7/8 Oclock positions. This can also be used on any 1 diameter accessories like 1 scope tube bodies, flashlights, and lasers. Mounts onto magazine tube with the two provided Allen head bolts. Installation may require user to disassemble shotgun barrel, magazine tube/end cap/ clamp.