The Shuttle Ejection Escape Suit used from STS-1 (1981) to STS-4 (1982) by a two-man crew used in conjunction with the then-installed ejection seats. It allowed ejections up to Mach 2.7 and 24.4 km (80,000 ft). The suit was manufactured by the David Clark Company of Worcester, Massachusetts. It was derived from the USAF Model S1030 suit, which at the time, was being worn by SR-71 pilots. Both the ejection suits and ejection seats were removed after the Shuttle became certified.