December 1, 2006: The U.S. Air Force has ordered another 12,889 Joint Direct Attack Munition (JDAM) tail kits. Each will cost about $23,000. These kits are attached to 500, 1,000 or 2,000 pound unguided bombs, to turn them into "smart bombs." The tail kits contain the fins, electric motors to move the fins, batteries to run the motors, GPS and inertial guidance systems to let the guidance computer know where the bomb is in relation to the assigned target. In the last eight years, the air force and navy have received over JDAM 150,000 tail kits. This new order will be delivered in 2008 and 2009.