The XS Big Dot Night Sight is a defensive tritium sight designed to enhance your Remington 870 shotgun with yellow tritium illumination for superior low-light visibility. Features a proprietary photoluminescent Glow Dot that absorbs ambient light and provides bright illumination when you need it most.XS Big Dot Night Sight for Remington 870Yellow tritium front sight for enhanced low-light performanceBig Dot front measures 0.188 inches for quick target acquisitionFits shotguns with .125 to .140 diameter bead sightPhotoluminescent Glow Dot absorbs ambient lightDurable CNC machined steel construction12-year warranty on tritiumIdeal for defensive applications these sights help solve visibility issues from aging eyes to deteriorating vision providing big bright and easy-to-see aiming points day or night.