The Brodie helmet is a steel combat helmet designed and patented in London in 1915 by John Leopold Brodie. A modified form of it became the Helmet, Steel, Mark I in Britain and the M1917 Helmet in the US.

Here 2 examples of such helmet from the full spectrum of conditions.

The first one is in battle field condition, but retains the unit markings of the 2nd Infantry Division  of the American Expeditionary Forces (AEF). No visible markings.

The second one is in “mint” condition for its age. The helmet retains full paint and has markings in the rear rim. Full leather chin strap and interior. Size 7 1/2. Makers mark "268 ZD"