A security tag, comprising: a vial to contain a detrimental substance; a tag body including a vial compartment (92, 94) to contain the vial; a channel extending from the vial compartment (92, 94) to the outside of the tag body, characterized in that the tag body comprises: - means for attaching said tag body (1 A) to an article, said attaching means having a part which is received in said tag body; - means within said tag body for releasably preventing said part of said attaching means from being withdrawn from said tag body; - means within said tag body defining an arcuate channel leading from the exterior of said tag body to said preventing means, said arcuate channel being adapted to receive and guide an arcuate probe to said preventing means for releasing said preventing means from preventing said part of said attaching means from being withdrawn from said tag body; - a detectable electronic article surveillance ("EAS") sensor, and - abutment means within said arcuate channel for preventing the insertion of a relatively rigid wire into said arcuate channel far enough to release said preventing means, the rigid wire formed substantially in the arcuate shape of said arcuate probe. a vial to contain a detrimental substance; a tag body including a vial compartment (92, 94) to contain the vial; a channel extending from the vial compartment (92, 94) to the outside of the tag body, characterized in that the tag body comprises: - means for attaching said tag body (1 A) to an article, said attaching means having a part which is received in said tag body; - means within said tag body for releasably preventing said part of said attaching means from being withdrawn from said tag body; - means within said tag body defining an arcuate channel leading from the exterior of said tag body to said preventing means, said arcuate channel being adapted to receive and guide an arcuate probe to said preventing means for releasing said preventing means from preventing said part of said attaching means from being withdrawn from said tag body; - a detectable electronic article surveillance ("EAS") sensor, and - abutment means within said arcuate channel for preventing the insertion of a relatively rigid wire into said arcuate channel far enough to release said preventing means, the rigid wire formed substantially in the arcuate shape of said arcuate probe. - means for attaching said tag body (1 A) to an article, said attaching means having a part which is received in said tag body; - means within said tag body for releasably preventing said part of said attaching means from being withdrawn from said tag body; - means within said tag body defining an arcuate channel leading from the exterior of said tag body to said preventing means, said arcuate channel being adapted to receive and guide an arcuate probe to said preventing means for releasing said preventing means from preventing said part of said attaching means from being withdrawn from said tag body; - a detectable electronic article surveillance ("EAS") sensor, and - abutment means within said arcuate channel for preventing the insertion of a relatively rigid wire into said arcuate channel far enough to release said preventing means, the rigid wire formed substantially in the arcuate shape of said arcuate probe.