Engineered specifically for 40mm grenade launchers with Picatinny/Weaver rails, Meprolight's Mepro GLS Reflex Sight for 40mm GLS comes with several design features that help get you on-target including a 2 MOA impact point correction, and 180 MOA windage and 320 MOA elevation adjustment ranges. M203 ammunition has a tendency to drift sideways during flight, so the sight is pitched at a 2° angle relative to the rail to compensate this ballistic effect. A scale on the front riser represents the distance of impact in meters to aid in aiming.
A simple orange 4.3 MOA aiming dot employs a battery-free dual illumination system that uses fiber optics to focus ambient light when its available, or a radioactive tritium system in low or no light. These are passive systems so they are always on and transitions from one source to the other are instantaneous and automatic without needing to fumble for switches or dials.