The better you can see your sights, the better you can shoot.Tfo pairs truglo's fiber-optic sights with our tritium night sights to create a consistently bright sight picture day or night.This patented combination of tritium and fiber-optic technologies unites the best of both worlds providing the same bright sight picture whether you are in glaring daylight or complete darkness.This high mount model is compatible with glock 20/21/29/30/31/32/37 excluding mos models.Rear Color: GreenType: Front/Rear SetFrame Material: SteelFrame Color: Nitride FortressFirearm Fit: Glock 21Style: Square Front/U-Notch Rear High SetFront Material: Tritium/Fiber OpticRear Material: Tritium/Fiber OpticFront Color: GreenFirearm Type: Handgun