This spacesuit is an MD-1 suit that the David Clark Company manufactured for baseline engineering at the U.S. Air Force's request in 1966. At the time the USAF was planning for a Manned Orbiting Laboratory (MOL) human spaceflight program that would send pilots to a military reconnaissance and surveillance space station. The David Clark Company was one of several companies that created prototypes for the program. David Clark based its suit on the successful Gemini G4-C suit.
The USAF cancelled the program and turned over much of the existing hardware to NASA. NASA in turn donated this suit and others from the program to the Museum in the 1970s.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.