The P helmet, PH helmet and PHG helmet superseded the Hypo Helmet. The P Hood and the PH Hood looked identical, the later pattern was dipped in an extra chemical for extra protection.

The P (or Phenate) Helmet, officially called the Tube Helmet, appeared in July 1915, replacing the simpler Hypo Helmet. It featured two mica eyepieces instead of the single visor of its predecessor, and added an exhaust valve fed from a metal tube which the wearer held in his mouth. The exhaust valve was needed because a double layer of flannel – one treated and one not – was needed because the solution attacked the fabric.

It had flannel layers of cloth-dipped in Sodium Phenolate and Glycerin and protected against chlorine and phosgene, but not against tear gas. Around 9 million were made.

The PH Helmet (Phenate Hexamine) replaced it in October 1915, and added Hexamethylene Tetramine, which greatly improved protection against phosgene[3] and added protection against Hydrocyanic Acid. Around 14 million were made and it remained in service until the end of the war by which time it was relegated to second line use.

The PHG Helmet appeared in January 1916 and was similar to the PH Helmet but had a facepiece made of rubber sponge to add protection against tear gas. Around one and a half million were produced in 1916–1917.

The P PH & PHG Helmets were often called Hoods and both would be carried in the cotton smoke hood pouch, over a soldier’s shoulders. If the hoods got wet, it could make them useless in a gas attack.To protect their smoke hoods soldiers made them selves waterproof pouch liners (out of rubberised cotton fabric same as the ground sheets and capes) to carry inside the smoke hood pouch.

It was finally superseded by the Small Box Respirator (SBR) in Late 1916, which was much more satisfactory against high concentrations of phosgene or lachrymators.