Unfortunately the chairs are not adjustable: I found the base too high for my legs and the back too low. As a result the chairs are extremely uncomfortable, unless you happen to have very long legs and a short torso. The design need to be brought up to date for the 21st Century by being made adjustable.
The uncomfortable seating may be deliberate, as the NLA has a 2 minute video loop running. If you sit for more than a few minutes you will be driven to distraction, hearing the same thing over and over again.
These chars are also on permanent exhibition at the National Museum of Australia.