The XS DXT Big Dot tritium night sight is the ultimate defensive sight set. It features a Big Dot Tritium front sight and express rear sight with a vertical tritium stripe for fast sight acquisition in all light conditions. Big Dot demands your attention - even in high stress and for those with poor eyesight, aids in rapidly achieving combat effective hits. White dot reflects ambient light for best visibility in low light. Shallow V-Notch rear provides an unobstructed view of the front sight, along with a greater field of view down range, especially when moving and shooting. Day-Light, Half-Light, or Low-Light, just "dot the i" and center the dot over your target within 15 yards. Outside Diameter Big Dot 0.188"; fits in common holsters. NOTE: XS Suppressor height sights will work with suppressors up to 1.375 in diameter and the Trijicon RMR as long as the battery box height is not above 0.250 above top of slide. In most installations it will not work with the Vortex Venom/Viper, and Burris Fast Fire Optics.