840/841C Is a fast-opening, motorized hook bolt lock that can be used as a night and safety-lock, or as a daytime lock on doors in high security (RC3) commercial, offices and industrial premises. Features an extremely fast opening speed of approximately 0.2 seconds. Hook bolt (840) and lever latch (841) are designed for increased strength and side pressure, providing high security. Can be opened with a key or thumb turn. Can be combined with other devices using DAC, both in Hi-O installation with ARX and stand-alone, for example, daytime lock, automatic doors and card readers. Available without a lever latch making it suitable for use with automatic doors. When used as night and safety lock, doors should be supplemented with a daytime lock, such as an ASSA electric strike.