EVA from the shuttle, the cabin pressure was reduced from for 24 hours, after which an astronaut had to pre-breathe for 45 minutes. For EVAs on board the ISS, the astronaut must pre-breathe for about four hours. Specifications Baseline EMU Manufacturer: ILC Dover (suit) and Collins Aerospace (primary life support systems) Missions: STS-6 (1983) to STS-110 (2002) Function: orbital extra-vehicular activity Operating pressure: 4.5 psi (29.6 kPa) EVA suit weight: 109 lb (49.4 kg) Total shuttle EVA suit weight: 254 lb (115 kg) Primary life support: 8 hours (480 minutes) Backup life support: 30 minutes Enhanced EMU Manufacturer: ILC Dover (suit), Collins Aerospace (primary life support systems) and NASA (SAFER) Missions: 1998 to present Function: orbital extra-vehicular activity Operating pressure: 4.5 psi (29.6 kPa) EVA suit weight: 122 lb (55.3 kg) Total shuttle EVA suit weight: 275 lb (124.7 kg) Total ISS EVA suit weight: 319 lb (145 kg) Primary life support: 8 hours (480 minutes) Backup life support: 30 minutes Manufacturer The EMU hardware and accessories (PLSS, helmet, communications cap, and locking rings for the helmet and gloves), is manufactured by Hamilton Standard (now the Hamilton Sundstrand division of Collins Aerospace) out of Windsor Locks, Connecticut, while the suit's soft components (the arms of the HUT and the entire LTU) are produced by ILC Dover (a former division of Playtex) out of Frederica, Delaware. The two companies, who were rivals during the early days of Apollo for the contract to build the "Block II" (moonwalking) space suit, teamed up in 1974 against the David Clark Company and Garrett AiResearch for the EMU development and construction. During Apollo, the ILC Dover-produced A7L used the life support backpack, helmet, and locking rings supplied by Hamilton Standard, but originally, ILC Dover was to just supply the arms and legs of the suit, a similar process that is still going on today. In total 18 EMU suits with PLSS were manufactured; 5 were lost during missions, 1 was lost in ground test, and, as of 2017, 11 remain complete and functional. History Upon receiving the contract to build the EMU in 1974, Hamilton Standard and ILC Dover delivered the first EMU units to NASA in 1982. During the research and development phase (1975–1980), a suit being tested caught fire, injuring a technician and forcing a redesign on the regulator and circulation fan. On STS-4 in July 1982, the astronauts practiced donning and doffing