Progress-M1 (Russian: Прогресс-М1, GRAU indices 11F615A55 and 11F615A70), also known as Progress 7K-TGM1, is a Russian spacecraft which is used to resupply space stations. It is a variant of the Progress spacecraft, derived from the Progress-M, but modified to carry more UDMH and N2O4 propellant for refuelling the International Space Station instead of other cargoes such as water. A Progress M1 11F615A55 spacecraft could carry up to 1,700 kilograms (3,700 lb) of propellant in eight mid-section refuelling tanks, compared to the 850 kilograms (1,870 lb) that a Progress-M of the same generation could carry. This propellant can be transferred to the Space Station's own propulsion system through fluid connectors in the docking ring, or it can alternatively be used by the Progress' thrusters to