The Apollo/Skylab space suit (sometimes called the Apollo 11 Spacesuit due to the fact that it was most known for being used in the Apollo 11 Mission) is a class of space suits used in Apollo and Skylab missions. The names for both the Apollo and Skylab space suits were Extravehicular Mobility Unit (EMU). The Apollo EMUs consisted of a Pressure Suit Assembly (PSA) aka "suit" and a Portable Life Support System (PLSS) that was more commonly called the "backpack". The A7L was the PSA model used on the Apollo 7 through 14 missions. The subsequent Apollo 15-17 lunar missions, Skylab, and Apollo–Soyuz used A7LB pressure suits. Additionally, these pressure suits varied by program usage. For the Skylab EMU, NASA elected to use an umbilical life support system named the Astronaut Life Support Assembly. Basic design The base Apollo EMU design took over three years to produce. At the beginning of the Apollo program, the Apollo spacesuit had not yet received its final EMU. NASA held a competition for the Apollo SSA contract in March 1962. Each competition proposal had to demonstrate all the abilities needed to develop and produce the entire SSA. Many contractor-teams submitted proposals. Two gained NASA interest. The Hamilton Standard Division of United Aircraft Corporation proposal offered Hamilton providing the SSA program management and PLSS with David Clark Company as the PGA provider. The International Latex Corporation (ILC) proposal planned International Latex as the SSA program manager and PGA manufacturer, Republic Aviation providing additional suit experience and Westinghouse providing the PLSS. After evaluation of the proposals, NASA preferred the Hamilton PLSS concept and program experience but the ILC PGA design. NASA elected to split the Hamilton and ILC teams, issuing the contract to Hamilton with the stipulation that ILC provide the PGA. By March 1964, Hamilton and NASA had found three successive ILC Apollo PGA designs to not meet requirements. In comparative testing, only the David Clark Gemini suit was acceptable for Apollo Command Module use. While the Hamilton PLSS met all requirements, crewed testing proved the life support requirements were inadequate, forcing the Apollo SSA program to start over. In October 1964, NASA elected to split the spacesuit program into three parts. David Clark would provide the suits for the "Block I" early missions without extra-vehicular activity (EVA). The Hamilton/ILC program would continue as "Block II" to support the early EVA missions. The pressure suit