Tritium night sights transition from standard white dot sights during the daylight, to glowing green dots in the dark. Tritium does not need batteries. Fits most standard holsters. Front sight FOCUSLOCK ring for even faster focus. Fits most standard holsters. Front Sight Length: 1.0". Front Sight Width: 1.0". Front Sight Height: 1.0". Rear Sight Length: 1.0". Rear Sight Width: 1.0". Rear Sight Height: 1.0". Compatible w/Glock 20/21/25/29/30/31/32/37/40/41 Except MOS.