From my Samples, Singulars, and Somethings Completely Different collection -

Painted mild steel with heavy nasal and reinforcement bands, butted maille drape wired in place. Includes padded liner. Provenance and armorer unknown. I can't get my micrometer past the band onto the shell, but it feels like the body of the helmet is 16 gauge. Weight = 4 lb 6.5 oz