XS Sights XS Standard Dot, Fits Vent Ribbed Shotgun Barrels, Green Dot SG-P001S-1G The XS Vent Rib replacement bead is bright" durable" and an easy DIY install for all shooters. The universal fit design utilizes a friction tapper lock design that will securely hold the bead on the barrel for countless hunts or thousands of clays. The brass post comes in three sizes to cover the majority of shotgun threads available. The green or orange photoluminescent Ember Glow Dot is brighter than fiber optic light pipes in daylight and the dot glows in low light to enhance visibility during dusk or dawn hunts.