Made with 1.5mm Manganese steel, the Swiss M18 was a solidly made helmet, similar in design to the German M16 and traces of the US No 5 "Deep Salade" experimental of 1917. Over 600,000 of these helmets were produced, all being withdrawn in 1944 to have the olive green paint replaced by a sawdust mixed black paint. These earlier M18's had a deeper side skirt than the later M18/40 and full circle liner band as opposed to a 3/4 band of the later models. The small "K" stamped into the liner skirt is an abbreviation for the manufacturer "Carl Kyburz" of Bern. A date of 1932 can be found under the front liner pad, and the name "P Rotzetter" written in pencil under the liner pad..