内鍵 うちかぎ
uchikagi

Noun

1. internal lock

自宅 じたく改築 かいちくする さいに、この部屋 へやにだけ防音 ぼうおん設備 せつび内鍵 うちかぎ けたんだ。
jitakuo kaichiku suru saini kono heyanidake bōonsetsubito uchikagio tsuketa nda.
When my home had an extension built I only had this room fitted with soundproofing and an internal lock.