iron band; metal hoop
Refers to a band or hoop made of iron, often used for binding or reinforcing objects such as barrels, wheels, or wooden structures.
樽には帯金がはめられている。
The barrel is fitted with an iron band.
Compound of 帯 (obi, 'belt, band') and 金 (kane, 'metal, iron'), with rendaku voicing of 金 to がね.