The M7 Headwound Mask was the Army's first effort to provide a gas mask for wounded soldiers whose bandages interfered with the fit of a standard mask. It was essentially a clear plastic bag hood with an outlet valve and the M11 lightweight canister, The M7 Headwound Mask was standardized in 1944.
The M7 Headwound Gas Mask was developed after the invasion of France in June 1944. As casualties came in, it was realized that many head wounds made it impossible to fit any of the standard gas masks since either bandages or the wound itself prevented proper placement of the facepiece.
The headpiece was made of two sheets of Vinylite (a clear plastic sheeting), heat-sealed at the seams to form a closed, one-piece bag. The resulting one-size-fits-all hood has a rounded top to fit the head while the bottom opens out to fit the neck down to the chest of the wearer. A rectangular, transparent eyepiece is fitted in front along with a mount for the M11 canister at center front and an outlet valve to the wearer's left.
Plastic attachment points are affixed at four places on the hood and one on the neck for web strap assemblies. The straps are used to pull the mask into as comfortable of a shape as possible once the mask is in position on the patient. The neck strap must be pulled as tight as possible with the plastic pressed smoothly against the patient's skin for a gas-tight seal. If the patient had neck wounds, the final step was to seal the mask to the chest with strips of adhesive tape.
Only about 10,000 of the M7 Headwound Gas Mask were produced. It was replaced by the M18 Headwound Protective Mask in 1959.