The U.S. Air Force has bought another five MQ-9 Predator B UAVs, for $8.3 million each. The original Predator cost $4.5 million each. The "B" model has less endurance (24 hours compared to 40 hours for the A model), but carries more munitions (1.7 tons). Weapons carried include Hellfire missiles, and 250 or 500 pound smart bombs. Typically, the Predator B will go into action carrying 16 Hellfire missiles. The Predator B is meant to be a hunter-killer UAV. It will go into action looking for targets it can immediately attack. The Predator B has been undergoing tests in combat zones for over five years.