Why The HK USP Is The BestThis unique configuration increases visibility and quickens front sight acquisition-even in transitional lighting. Trijicon hd tritium sight for h&k usp compact yellow front 3 dot green hk108y the three dot green tritium night sight set’s front sight features a taller blade and an aiming point ringed in photoluminescent paint while the rear sight is outlined in black and features a wider u-shaped notch.