The RAF's VC10 tanker force operates four variants of the aircraft: the C1Ks are military transport aircraft, carrying 120 passengers or freight, and can be adapted for tanking with the addition of wing-mounted refuelling pods; the K2s are ex-civil VC10s and the K3s and K4s are ex-civil Super VC10s although the K4s lack the additional fuselage fuel tanks of the K3s. The K2s, 3s and 4s all have wing refuelling points for fighters and a centerline refuelling capability to provide additional support for large aircraft.