The M-970 Semi-Trailer Refueler is a 5,000-U.S.-gallon (19,000 L; 4,200 imp gal) fuel dispensing tanker designed for under/overwing refueling of aircraft. It is equipped with a filter/separator, recirculation system and two refueling systems, one for underwing and one for overwing servicing. The tanker is designed to be towed by a 5 ton, 6x6 truck tractor or similar vehicle equipped with a fifth wheel. The M-970 can be loaded through the bottom or through the top fill openings.