The hybrid design of this magnetic electromechanical lock includes two spring loaded, hardened steel jaws that deliver up to 4, 000 lbs of ultimate holding power. In a forced-entry assault, the jaws of the MM15 Memlock clamp down on the armature plate and hold firm, for an unmatched level of access control. Ideal for mental healthcare and auxiliary detention facilities and other high-risk locations. Automatic dual-voltage, no field adjustment required. Mounting plate for easy, accurate installation. Size optimized for use with door closers. Accepts AC or DC current. Ultra-secure collapsing blind nuts mount to door frame for strength and reliability. UL 10C Fire Rated, 1 hour.