Original U.S. Vietnam War Era HGU-26/P “Phantom-1” Flight Helmet with MS-22001 Oxygen Mask and Helmet Bag Price_$220 - $990 The rear of the tunic

The rear of the tunic is single-vented

It is marked size 7 3/8 on the support strap in the middle

The bottom of the shell is marked P181 WaA84 Xw 40 45

which is what the number 564 corresponds to

with a HERBERT JOHNSON LONDON manufacturer's stamp in the dome

Original U.S. Vietnam War Era HGU-26/P “Phantom-1” Flight Helmet with MS-22001 Oxygen Mask and Helmet Bag Price_$220 - $990 The rear of the tunicOriginal Item: One of a kind. The HGU 26 P request for nomenclature is dated Jan 14, 1970 and is based on the HGU 22 P Helmet Shell. There is no military specification detailing exactly what goes into an HGU 26 P but until the appearance of the single visor HGU 26 P both USAF and manufacturer information was consistent in describing the HGU 26 P as an HGU 22 P helmet shell with a PRU 36 P side actuated double visor. Sierra Corp and Gentex Inc sold