The Mutual Time Delay lock has been designed to maximise versatility with ease of installation and operation. It can be fitted onto new or existing security installations. The time delay period can be preset to suit differing needs ranging from a 5 minute delay to a maximum of 30 minutes. Once this period has lapsed, the lock with remain in ready-to-open mode for a further 4 minutes after which it will automatically re-lock itself. This delay period cannot be shortened or overriden once it has been programmed meaning there is no alternative to waiting until the count-down period has lapsed.