First developed by ITT in 1992, the F4949 night vision system continually has improved and is now designated the AN/AVS-9(V) by the U.S. Government. The (V) indicates there are many versions in service. The F4949 series is the standard night flying system for the air crews of the U.S. Air Force and Navy. Over 26,000 F4949 systems are in service in 34 nations, worldwide. Rotary-wing versions of the F4949 feature a rear-mounted, low-profile battery pack, which uses four AA alkaline batteries, allowing operation for more than 50 hours. Power is provided by a cable extending from the battery pack, over the helmet, and into a connector in the mount. Fixed-wing versions feature a front-mounted battery pack, which uses two 1/2 AA lithium batteries that allow operation for more than 16 hours. An optional battery pack adapter enables connection of the fixed-wing F4949 to the rear-mounted battery pack, providing the same operational time as the rotarywing versions when ejection is not a consideration. An optional clip-on power source enables hand-held operation of the binocular without use of a flight helmet. ITT's F4949 series of aviator's night vision systems is available in over 40 different configurations. The type of aircraft and type of helmet being used will determine which configuration – existing or customized – will best meet our customer's requirements.