AmeriGlo Rear Only-Green Tritium Lamp 2-dot Black Outlines .429" H .150 Sq Notch fits MOS slide. Because in the dark your regular sights just aren't good enough. With an AmeriGlo Glock Classic Style Tritium Rear Sight you can turn the night into day. Tritium is an invaluable aiming resource because in the dark the sight gathers light from the small studs on the front of the sight thus illuminating it without the need for any battery or external power source. This allows your sight to run much longer before having to be manually adjusted maintained or zeroed. Advanced manufacturing of the Tritium creates a brighter and more effective aiming system. Plus the sight body is a perfect fit for most standard holsters. Snag & LockTM TechnologyNOTE: This product is not a night sight nor is it legal for general use as it requires a night or dark-adapted vision to install. Specifications for AmeriGlo Glock Classic Style Tritium Rear Sights: Manufacturer: AmeriGlo Color: Black Sight Style: Square-Notch Package Contents: AmeriGlo Glock Classic Style Tritium Rear Sights AmeriGlo GTR-209: Rear Only-Green Tritium Lamp 2-dot Black Outlines .429" H .150 Sq Notch fits MOS slide