| has gloss | eng: A key retainer device (KRD) is a small metal unit that is wall or door mounted, usually designed for the interchangeable core that retains one key (Key A) while the second key (Key B) is used for authorized purposes. When the key in use (Key B) is returned into the key retainer, the key held captive (Key A) is turned and then can be released. Now, the special key, perhaps top master (Key B) is held captive again. The key retainer is an excellent method for providing visual key control. |
