Ives 3CB1 4.5″ x 4″ 640/10B TW4, Full Mortise Ball Bearing. • One hinge per box, packed with wood and machine screws• Hinge is NRP as a standard• High quality brass ferrules and plastic tubing protect the wires• Through-wire hinges cycle tested to ensure durability• 2 ball bearingThrough-Wire is rated for 50 volts AC/DC at 3.5 amp continuous and 16 amp pulse, maximum pulse 400 mili second.Monitor rated 30VDC at .5 amp