Stahlhelm (plural, Stahlhelme) is German for "steel helmet". The Imperial German Army began to replace the traditional boiled-leather Pickelhaube (spiked combat helmet) with the Stahlhelm during World War I in 1916. The term Stahlhelm refers both to a generic steel helmet, and more specifically to the distinctive (and iconic) German design.
The Stahlhelm, with its distinctive "coal scuttle" shape, was an instantly recognizable icon for military imagery and became a common element of military propaganda on both sides, just like the Pickelhaube before it.
When Gustav Hozzel joined the German Emergency Militia at the outbreak of World War III, he was issued an American styled helmet. He disliked it since it didn't cover as much of his head as the WehrmachtStahlhelm but kept it after the Soviets killed in cold blood a few Stahlhelm-wearing militiamen and left swastika placards by the bodies.