"Tranquility" was built within the ESA-NASA ISS bartering system. ESA committed to build and fund both "Harmony" and "Tranquility" as well as the ATV in order to use NASA ISS facilities, fly astronauts on the Shuttle and for other ISS services. ESA teamed up with the Italian Space Agency (ASI) to manufacture both "Harmony" and "Tranquility" at Thales Alenia Space in Turin, Italy. The module pressure shell is constructed of 2219 aluminum and its debris shield is made from hardened 6061 aluminum. The metal is heat-treated, enabling it to have similar ballistics resistance to stainless steel.