This is an ILC Industries Apollo A2-L developmental spacesuit submitted to NASA prior to 1965. The silver coverlayer on the suit indicates that it was used for thermal testing. At the time, the plan had been for the astronauts to wear the pressure layer of the suit and add the thermal micrometroid garment (TMG), the coverlayer, only in preparation for a spacewalk.
NASA transferred this spacesuit to the Museum in 1985.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.