This is an example of the portable life support system (PLSS) worn by astronauts on the moon. It is without the Oxygen Purge System (OPS) which would have been attached to the upper portion of the PLSS.
The PLSS was used for water and air circulation, communications, and oxygen "scrubbing". It weighed approximately 65 lbs and all the units used during the Apollo missions were left on the lunar surface due to weight considerations.
The OPS was used for oxygen storage and circulation. The components in this example are color-coded to show the interior components and how they worked and connected to each other.
NASA - Johnson Space Center transferred to the museum in 1983.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.