The M21-X with X reticle reflex sight provides constant, all-light aiming capability, without batteries. Designed through close collaboration with Israeli Special Forces, the M21 was the first reflex sight in the world designed for close quarter combat. It is battle proven, reflexive to use, deadly accurate, and totally reliable. The M21s large 30mm diameter lens allows rapid target acquisition with both eyes open. Reticle illumination is achieved by a protected fiber optic light collector system during the day, and by a self-powered tritium light source at night. Transition between the two systems is instantaneous and automatic to assure good contrast between the aiming dot and the target area. The M21 is night vision compatible. This sight gives shooters the ability to acquire targets accurately at any range, in any situation, with both eyes open. It is compatible with magnifiers.