From Aimpoint:

In 2006, the US Army's Armament Research Development and Engineering Command (ARDEC) ran a series of competitive tests to find out if there was another sight out there that could surpass the performance of the existing M68CCO sights. Every manufacturer of combat optics sent samples for testing, and when the results were finalized, Aimpoint was once again awarded a new contract for 163,000 of this new sight - the CompM4.

The Aimpoint CompM4 is now the latest version of the US Army's M68 CCO (Close-Combat Optic), continuing the legacy that Aimpoint has maintained since 1997. The CompM4 is the finest sight that Aimpoint has ever produced. Improvements include increased energy efficiency that provides over 8 years of continuous use from a single AA battery!

The CompM4 incorporates an integral mount that eliminates the need for a separate ring, and can be customized with vertical and forward spacers to fit a variety of firearms. Primarily designed for use by law enforcement and military units, the CompM4 is a great choice for competition shooters and hunters looking for a rugged sight for predator hunting or other low-light applications.

The performance of the Aimpoint CompM4 is optimized for use with all generations of night vision devices (NVDs), but is especially suited for 3rd generation night vision technology. Aimpoint's unique band-pass coating on the front lens gives the highest possible dot brightness with the smallest amount of energy while providing the clearest, brightest image possible when used with a 3rd generation NVD. With 7 NVD-compatible brightness settings and 9 Daylight settings including one extra-bright setting, the CompM4 is ready for duty 24/7.