XS Sights DXT2 Big Dot Tritium Front, White Stripe Express Rear, Fits Sig Sauer Models: P225, P226, P229, P320, Springfield XD, XDm, XDs, Green with Yellow Outline SI-0013S-5Y XS DXT2 Big Dot 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. DXT2 Big Dot 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. Optic Yellow is the best option for low light and has the brightest glow intensity. Primarily based on the white light spectrum" optic yellow is very reflective and will excite the photoluminescent properties of the dot faster than any other color. The increased surface area of the convex dot increases light absorption" intensifying the charge of the glow properties of the dot. The dot-the i sight picture" with a tritium dot in the front sight and a tritium bar in the rear" prevents confusing the front and rear sight in high-stress situations. The wide field of view increases visibility of the front sight and of the threat downrange.