Built with the dynamic handgun shooter in mind, the Trijicon HD is a three dot green tritium night sight set where the front sight has a photoluminescent paint outline that draws your focus to it. With an attention grabbing front sight and a wider u-shaped notched rear sight, this configuration allows for quicker sight acquisition and increased visibility. The rear sight is also designed with a steep hook for one hand slide manipulations off a belt or holster. The tritium lamps are also warranted by Trijicon for 12 years from date of manufacture, Specifications and Features: Trijicon HD Night Sight Set SG103Y 3-Dot Green Tritium Night Sights Yellow Front Sight Outline U Notch Rear Sight Front blade width 0.144" Front blade height 0.225" Rear notch width 0.169" Rear sight height 0.218" Steel Black Fits: SIG #6 Front/ #8 Rear P220/P227/P229/P240/P245 chambered in .40/.45