Abstract: A panel element (2) for use in constructing a shelter is disclosed. The panel element comprises a body portion (4), first locking means (8) mounted to the body portion, and second locking means (6) mounted to the body portion. The first locking means comprises an elongate member (10) having a plurality of apertures (8) therein, and the second locking means comprises a plurality of locking elements (6) moveable relative to the body portion between a storage position and a deployed position. In the deployed position, the locking elements engage respective apertures of a first locking means of a further panel element to urge the further panel element towards the first panel element.