a first set of pivoted latching fingers having hook ends facing in a first direction are provided , together with a second set of pivoted latching fingers interlaced with the first set in accordance with a particular combination which unlocks the device . the fingers of the second set of latching fingers have hook ends facing in a direction opposite to the direction of orientation of the hook ends of the first set and actuation of only the proper combination of fingers causes the hooks of all fingers to be displaced away from a pair of facing lock anchor members to unlock the lock . all of the fingers are pivoted so that slight amounts of magnetically permeable material in the card key are sufficient to move the hooks of the pivoted latching fingers bearing permanent magnets , through a substantial distance , to enable the use of a thin , flexible card key for positive lock actuation . additionally , slidable elongated hook protrusions may be selectively positioned to extend from the fingers in first or second directions , to enable changing the lock combination in a matter of seconds by inserting a new key card into the lock after all of such protrusions assume a first position with respect to all fingers .