An anti-theft tag has two slightly concave shells attached to each other by a hinge. One shell has an aperture through it and the other shell has a post located to insert through the aperture when the two shells are brought together. At least one catch tab extends laterally from the end of the post. The catch tab exceeds the width of the aperture and is constructed to give to allow the post to insert into the aperture, but to resist and prevent the extraction of the post. The post is severable to allow the remove of the catch tab to allow the opening of the tag. One of the shells also has a slot and the other has a tack. When the post is inserted through the aperture, the tack inserts into the slot. The tack passes through an object to be protected and maintains the tag in place.