This is a vintage Norwalk Lock Co. mortise lock with a brass faceplate. An interior mortise lock is a lock that is set within the body of a door in a recess or mortise. Interior mortise locks commonly include a doorknob hub through which a doorknob spindle is installed and doorknobs are mounted on each side and secured into place with pins or set screws; and a keyhole which accommodates an old-fashioned bit or skeleton key which in turn throws the deadbolt to lock and unlock the door. Mortise locks have specific dimensions including backset, the measurement from the edge of the faceplate to the center of the doorknob hub; and spacing, the measurement from the center of the doorknob hub to the center of the round part of the keyhole. It is very important to note the dimensions of your door prior to purchasing a mortise lock. Weight: 1.5 lbs. Item Measurements: Faceplate: 1.125(L) x 6.25(H) x .25(W) Lock Body: 3.25(L) x .75(W) x 4.25(H) Backset: 2.75" Spacing: 2.25"