Abstract: A positioning device includes a fastener member fixedly mounted on a supporting post and having an abutting base protruding outwardly from a periphery thereof. A recess is defined in an end face of the fastener member. A substantially U-shaped adjusting rack includes a first arm adjustably mounted on the abutting base and a second arm. A flange protrudes outwardly from an end face of the first arm and is securely received in the recess.

Abstract: A lock housing with a key way blocking means for selectively blocking the key way includes a pair of meshing halve lock housings, and a circular ring turnably secured on one of the lock housing. The circular ring includes an aperture at one side which is sized and shaped in correspondance with the key way of the lock housing. When the circular ring is turned to a first direction, the key way of the lock housing is exposed outwardly for insertion of a legal key to unlock the lock. When the circular is turned to a second direction, the aperture of the ring departs away from and blocks the key way.

Abstract: The improved lock core comprises a cylindrical casing receiving a rotatable spindle formed with a co-rotatable outer ring through which upper plug followers extend, biased by lower plug followers received in a lower plug non-rotatably secured to the casing with a lock pin. A pair of protuberances are formed closely adjacent each other on an upper surface of an outer ring to receive a tenon of a valid key inserted through a key hole in the cylindrical casing. The protuberances enable the key to apply rotative torque to the outer ring while a front edge of the key depresses the upper plug followers a sufficient depth enabling the outer ring and spindle to rotate relative to the lower plug.