This bolt must be morticed into the door and used in conjunction with a security star key (sold separately) that turns and releases the bolt mechanism. Supplied with matching SS wood screws. Overall Length: 37mm Cylinder Diameter: 16mm Facing Plate Size: 43mm x 20mm x 2mm Receiver Plate Size: 43mm x 20mm x 2mm Oval Receiver Plate Size: 39mm x 20mm x 2mm Backset: 16mm