Big Dot and Standard Dot Night Sights are defensive tritium sights designed to enhance your defense gun. The sights use a proprietary photoluminescent Glow Dot that absorbs ambient light and glows in low light. The convex dot's additional surface area increases light absorption, intensifying the charge of the Glow Dot. Designed to be large and highly visible, these sights help solve many issues, from aging eyes to deteriorating vision. We've found that the orange front tends to be most visible in daylight settings and that yellow glows brighter in low light, while green is an excellent option for low light and has a very bright glow intensity. XS Tritium Night sights are big, bright, and easy to see day or night! The sights are CNC machined from solid steel bar stock by our in-house machine shop. We design, machine, and insert our tritium to produce the highest quality possible and provide American Made products. Product Features Tritium powered front sight Big Dot front measures 0.188" Standard Dot front measures 0.140" High-contrast colored front sight Glow dot absorbs ambient light and glows in low light Durable CNC machined steel 12 year warranty on tritium