The big dot tritium front sight improves sight acquisition speed and tritium enhances low-light use of the defensive shotgun.Glues over front bead and the bead must be 0.120"-0.140" in diameter.It may require opening up bead hole to larger size by drilling & tapping.Fits mossberg, remington and others with bead mounted directly to the barrel.The xs big dot tritium front sight is a stand alone solution and does not work with any rail or ghost ring solution.Type: Tritium FrontFrame Color: BlackFirearm Fit: Shotgun w/Plain BarrelFront Material: TritiumFront Color: Green w/White OutlineFirearm Type: Shotgun