Partial pressure type helmet, built by M.L. Aviation Ltd.

The MK.4 G was employed on F-104G of the German Luftwaffe for high-altitude missions.

The same type of helmet has been used for the first test flights of the British Concorde

The visor is spring loaded and operated manually by the yellow lever, or automatically by a mechanism controlled by an aneroid capsule.

In this picture the "clam shell" style construction is well visible.

Rear view. The rear shell is hinged on top and spring loaded.

Anti glare visor lowered. The visor is controlled by the lever located behind the main visor mechanism cover.

Once the rear shell opened, the double walled pressure bag zip fastener is easily reachable.

The emergency manual opening ripcord, actuated by pulling the release knob visible at the left.

Adjustment laces.

The interior double walled pressure bag.

From left to right: breathing hose and inlet valve, mouth access flap, breathing outlet valve.

Mouth opening hinged flap opened. To activate the flap, both catch mechanism release buttons must be pressed simultaneously.

Identification plate.

The helmet is stored in a cardboard box.