US WW1 helmet pieces of kit...some unknown

[browningautorifle]

The large spring was in the gas mask bag. I will likely post that under the "what is it" section of US Militaria as well as here and gunboards.

Here's a description of the job of that spring... "WW1 Gas Mask Carrier U.S. Army M1917 SBR Gas Mask Brown Canvas Carry Bag WWI Replica American CE Gas Mask Bag
This bag is based on the British WW1 gas mask bag the main difference between the British and American bag is the closing snap buckles on the front, the British one has press studs and the American has lift the dots.

Includes the heavy wire spacer spring that ensured proper airflow around the filter box.

CE stands for Corrected English.
When the US Army first entered World War One, they did not have any gas masks so they issued the French M2 gasmask but they quickly found they needed something better so by 1918 they where issued the British SBR (Small Box Respirator)."

So it holds the case open from bunching up and choking off the air to the filter.