Abstract: A pocket-knife having a blade which is pivotable between open and closed positions, and which is lockable in the open position, is disclosed. The pocket-knife comprises a handle, a knife blade pivotaly mounted at one end of the handle, a beam spring extending substantially along the length of the handle, and a locking device for locking the knife blade in the open position. The beam spring is pivotally mounted for limited rocking movement within the handle. The beam spring includes a recess for receiving a retractable locking member of the locking device, a projection or ratchet tooth cooperating with the locking member, and cam guide cooperating with a tang portion of the knife blade to control the pivoting of the knife blade. When the knife blade is in its extended position, a spring urges the locking member into the recess of the beam spring.