Abstract: The present re/desensitizer is an apparatus for changing the status of a magnetic marker of an electronic article surveillance system. The markers are attached to or otherwise associated with an object to be protected, such has a book, CD, etc. The device can be set up as a resensitizer, a desensitizer, or with the inclusion of a mode switch, a combination re/desensitizer. The apparatus includes a magnetic field generator for generating a marker status changing magnetic field, detection means for detecting presence of an object, a control means for controlling the activation time of the magnetic field generator such that the marker status changing magnetic field is generated when an object is present. The magnetic field generator includes an offset core designed for continuous operation without excessive heat build up.