Tritium night sights deliver incredible visibility because only Swiss tritium is used in the battery-free design. The glow-in-the-dark design is completely reliable, and the front sight Focus Lock rings makes locking onto the sights even easier. Tritium night sights use a quick and accurate U-notch design. Fortress Finish delivers a protective coating that lasts forever Angled rear sight for one-hand operation in an emergency Assembled in USA This tritium night sight is compatible with Novak handguns. Mfg: Truglo TG231N1W fits 1911 Models with NovakA(R) LoMount cut .260 Front/.450 Rear (1911 5" Government .45ACP)*RugerA(R) SR1911 Models with fixed rear sight. TG231N2W fits 1911 models with NovakA(R) LoMount cut .270 Front/.450 Rear (1911 5" Government 9mm/.40 S&W) TG231N3W fits 19