This optical sight was developed specifically for the United States Army and is in wide service on M240 and M249 machine guns. With the special M4 reticle option it can also be used on M4 carbines. The M145 differs from the standard 3.4x sight in that ballistic compensation is in the reticle, rather than in the mount. Reticle illumination is by a battery-powered LED with eleven intensity settings. The mount incorporates the U.S. Army torque knob attachment method and fits directly to any MIL-STD-1913 "Picatinny" rail or receiver. Zero is retained despite repeated removal and re-attachment to the weapon. The M145 passes all NATO tests for shock resistance and water immersion and comes equipped with an anti-reflection device and rubber lens caps. Laser filters are available for military customers only. Comes with a one-year warranty.