View of the helmet visor sealing system valve.
The valve on this helmet differs from the flight
configuration. Other helmets on display (e.g., Slayton's
have flight-type helmet visor sealing system valves.
The helmet visor sealing system consisted of a visor, a pneumatic visor seal,
and an on-off visor valve. Closing the visor actuated the valve and caused
automatic inflation of the visor seal. The visor seal remained inflated until
the deflation button on the valve (presumably the red button on the other
helmets' valves but missing from this particular valve) was manually actuated
by the astronaut.
Note the provision for the attachment of the visor-seal gas supply bottle hose
at the tip of the valve.