A tag having a magnetic clamp for use in securing an item in order to prevent the unauthorized removal of the item from, for example, a retail store. The magnetic tag includes an attachment element that secures the item to the tag. A clamp having a locking region secures the attachment element such that the item cannot be separated from the tag. A keyed magnetic element on the clamp includes one or more hard magnets, where each hard magnet has either an outward-facing north or south polarity. By applying a magnetic force to the magnets, the locking region moves away from the attachment element thus allowing the item to be removed from the tag. The arrangement of magnets operates as a “key” and only a detacher unit with an identical magnetic pattern can apply the requisite magnetic force to the magnets to disengage the clamp from the attachment element to allow removal of the tag from the item.