This is a Hazardous Environment Protective Assembly (HEPA) suit. Spacesuit manufacturer David Clark Company, Inc. made these suits for technicians testing spacesuits to wear while assisting astronauts and technicians in hypobaric chambers. Wearing the suits meant that they could enter the chambers before re-pressurization in case of an emergency. These suits resemble the Gemini spacesuits manufactured by David Clark.
NASA transferred this suit to the Museum in 1972.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.