Meprolight GLS HD 400M Grenade Launcher Optical Sight Stand Alone Top Mount - Qd Black. Simply superimpose the illuminated dot in the sight window onto the target and shoot. The internal compensating system factors in grenade spindrift and corrects for it. Achieving high accuracy day or night is no longer a problem. The lightweight compact unit mounts to Picatinny rails.The Mepro GLS 40 mm grenade launcher sight system provides the user with an accurate optic from 50-400m. (54-420 yd). Specifications for Meprolight GLS HD 400M Grenade Launcher Optical Sight: Manufacturer: Meprolight Color: Black Objective Lens Diameter: 40 mm Red Dot Sights-Footprint: Glock MOS Package Contents: Meprolight GLS HD 400M Grenade Launcher Optical Sight Meprolight 613256: GLS HD 400M Grenade Launcher Optical Sight Stand Alone Top Mount - Qd Black 613256