steel helmet
Refers to a military-style steel helmet, such as those used in wartime.
兵士たちは鉄兜をかぶって塹壕にいた。
The soldiers were in the trench wearing steel helmets.
Standard kanji spelling.
Mixed kanji-kana spelling; may be easier for learners.
Compound of 鉄 (てつ, 'iron, steel') and 兜 (かぶと, 'helmet').