noun
A metal fitting used for fastening, such as a buckle on a belt or a clasp on a bag.
このバッグの留め金具が壊れてしまった。
The buckle on this bag has broken.
ベルトの留め金具をしっかり締めてください。
Please fasten the belt buckle securely.
A broader term for any metal fitting or hardware; 留め金具 specifically refers to fastening hardware.
Compound of 留め (tome, 'fastening') + 金具 (kanagu, 'metal fitting').