A security tag including a flexible member that can be formed into a loop to attach the security tag to an article. A security tag comprises: a main body comprising a casing that comprises a first aperture proximate a first end wall and a second aperture proximate a second end wall; an elongate flexible member, a first end of the flexible member extending through the first aperture; a releasable locking mechanism in the main body and associated with the second aperture, the locking mechanism configured to retain a second end of the flexible member; and two electronic article surveillance sensors within the casing, the sensors on opposite sides of a plane disposed halfway between the first and second apertures. When the second end of the flexible member is retained in the casing by the locking mechanism, a centre of gravity of the main body lies in the plane.