The joint cross has four arms at right angles to each other and with an integral grip member (3) extending perpendicular to two opposite arms. One of the four arms (2) has an ideal break point (9) formed by upper and lower notches and running parallel to the relatively flat grip member (3). The grip can have a slit (6) extending over the entire height for hanging a plumb line or similar. The edges of the arms remote from the grip member are pointed. The cross can be made from plastics.
