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metal rod; metal bar; iron rod; crowbar
iron club; iron staff with rings on top (traditionally used by night watchmen)
工事現場で金棒を使ってコンクリートを砕いた。
At the construction site, a metal bar was used to break up concrete.
鬼に金棒とはまさにこのことだと感心した。
I was impressed and thought this was exactly what the saying about giving an ogre an iron club meant.
金棒のような重い道具を軽々と持ち上げた。
He effortlessly lifted a heavy tool like a metal bar.