The M5 flak helmet was the last aircrew flak helmet developed during WWII.
The metal is covered with a short fuzzy flocking to prevent skin sticking to metal at high altitudes (my camera can't pick it up),there is no brim compared to the M3 which resembeled the standard M1 GI helmet with rounded ear flaps. The ear flaps were more pointed on the M5. Another inovation was the clip added to the chinstraps attached to the swivel bails for quick easy repair. An inovation used on the standard M1 helmet post war.