Schlage Electronics M420P Traffic-Control Electromagnetic Lock, For Access Control Systems, Single Door, 500-lb. Holding Force Electromagnetic lock with a 500-lb. holding force connects to a door access system such as a push bar, request-to-exit device, or credential reader to create a secure locking system for a single inswing or outswing door while monitoring the strength and status of the locking mechanism Armature plate mounts flush to the door and pivots to compensate for slight irregularities, enabling it to come in contact with the electromagnet mounted below the top of the doorframe Automatic voltage selection feature distinguishes between a 12-or 24-VDC electrical connection and adjusts automatically, and the automatic surge suppressor protects the equipment from damage if voltage spikes Door-status and magnetic-bond sensors communicate with an access control system to identify an open or closed door and monitor the strength of the magnetic connection, and the lock can be programmed with a 0.5- to 30-second relock delay Fail-safe design loses magnetism and unlocks when power is removed