XS DXT2 Big Dot Tritium Night Sights offer the best front sight visibility in all lighting conditions. DXT2 Big Dot sights drive focus to the front sight using a high-contrast front and a V-notch rear for an unobstructed view of the front sight. The front sights use a patent pending glow dot that absorbs light and glows in low light levels before it is dark enough to see the tritium.