SK-1 is an initialism of "Skafandr Kosmicheskiy" # 1 (Скафандр Космический = "spacesuit" or "diving suit for space") is a spacesuit that was developed specially for Yuri Gagarin. As such, it is the first spacesuit ever used. After his successful flight on the Vostok 1 spacecraft, spacesuits of the SK series were used for space flights of other cosmonauts on Vostok spacecraft, in which the cosmonauts would eject and land separately from module. The SK-1 was used from 1961-1963.