a housing that is adapted to be fixedly mounted in the opening of the cabinet part, wherein said housing is provided with at least one projection adapted to axially engage at least one radially extending extension of the opening;

an operating shaft that is rotatably mounted in said housing, wherein a part of said operating shaft that is adapted to be disposed on an outside of the cabinet is adapted to be coupled with a closing or locking means;

a casement tongue fixedly connected to a part of said operating shaft that is adapted to be disposed on an inside of the cabinet, wherein said casement tongue is pivotable between a locking position and an unlocking position by rotation of said operating shaft between housing stops; and

a fastening means disposed on a part of said housing that is adapted to be disposed on an inside of a cabinet for fastening said housing to the cabinet part, wherein said fastening means comprises a locking ring that is axially displaceable on said housing part against the force of a spring supported on said housing, wherein said locking ring is disposed on said housing part so as to be fixed against rotation relative thereto, wherein said locking ring has at least one locking dog, wherein said at least one locking dog is offset relative to said at least one projection of said housing by an angle, and wherein said at least one locking dog has an inclined surface that faces a mounting direction of rotation of said housing and in a peripheral direction of said locking ring is inclined relative to a longitudinal axis of said casement lock.