Described herein is technology for, among other things, a theft deterrent apparatus for cooperation with an elongate member attached to and extending outwardly from a forward-facing side of an article display panel. The apparatus includes a housing defining an internal chamber. The housing includes a first aperture passing through the housing into the internal chamber for receiving the elongate member, a second aperture for receiving a magnetic key, and a locking member that has a magnetic portion and is movably disposed within the internal chamber. The locking member is adapted to selectively: maintain the apparatus in locked and unlocked configurations in which the locking member respectively prevents or permits the elongate member from being at least partially withdrawn from the first aperture. Whether the locking member maintains the apparatus in the locked or unlocked configuration depends on whether or not the magnetic key is inserted into the second aperture.