XS Sights Big Dot, Tritium Night Sight, Yellow Front, Fits S&W J-Frame with Integral Front Sight, Gunsmithing Required SW-0034N-3Y Big 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. The white dot does not glow but is reflective" so it is an excellent option for bright and low light. XS Tritium Night sights are big" bright" and easy to see day or night!