This helmet is a "DH-151 modifiziert PA-594-BAMF 2". The DH-151 shell is

similar to the HGU-22, fitted with HGU-55 components. Oxygen mask is a

MBU/5-P, connected to the helmet with "J" bayonets.

Some of those helmets are probably still in use. This assembly was an interim solution adopted in order to provide pilots with lightweight helmets, using

spare parts already available, before the introduction of the HGU-55.

The boom mike bracket, another classical modification of Swiss AF helmets.

The other parts needed to install the boom mike.