Twenty air force personnel spent 70 days erecting two portable hangers for maintaining B-2 bombers. Each shelter is some 600 feet long and has high performance ventilation, air conditioning and heating systems that allow the precise maintenance that must be performed on B-2s after each mission to preserve their stealth capabilities. The outer skin of the B-2s contain a special radar absorbing material that is damaged each time the aircraft flies. The B-2s could not operate overseas without this special post flight maintenance. The shelters were set up on the American bomber base at Diego Garcia island in the Indian Ocean. Subsequent set up time for the shelters will be shorter as this was the first time they were used in the field and problems were encountered that had to be taken care of before the shelters were ready for use. The shelters are built to withstand high winds and extremes of heat and cold.