Unlock your door with the push of a button - from the other side of the house or office! Designed for use with cylindrical lock- sets (commonly used on wooden and aluminium doors), it converts a conventional lock- set to an electronic access- controlled locking system. Benefits include higher security, and user convenience without needing to use a key. Both units are fail- secure - meaning that the door is locked with power OFF, and unlocked with power connected - suits entrance- door installation. Simply mounts in existing architrave - original lock- set can still be unlocked with key.