In 1966 Tianjin watch company set about developing the all new calibre ST5 and by 1968 the movement was put into mass production. The first series movements where made for DongFeng (东风) and was the first all Chines engineered and manufactured wrist watch. The company later changed name to Tianjin Sea-gull watch factory (天津海鸥手表集团公司) and these later movements got an interesting bridge decoration featuring hand engraved deep spiralling starburst pattern (Known as Sea-gull decoration). The ST5 met the National First Grade standard; At least 17 jewels, no excess of parts, beat rate starting at: 21800bph, 40hours power reserve and a minimum timekeeping of +-30 sec pr 24hours. This allowed the Tianjin factory an exemption from discontinuing the ST5 production in favour of the Chinese standard movements, that killed most of the other Chinese movements when it was introduced. In 1971 an autowinder mechanism was added to the lineup. (I have yet to review the Auto version of the ST5) The Seagull with the ST5 movement was entrusted to Chinas Antarctic expedition team that built the great wall Station on King George island in 1984.
Click on the link below to see the movement review