A cross arm unit for supporting wires such as in a grapevine supporting trellis. The cross arm unit has an elongated arm member which is secured to a socket member transversely related to the arm member. The end portions of the arm member are reverse curled with the ends being spaced from the remainder of the arm member to provide wire-passing slots. In one form of the invention the socket member is of square cross section with the arm member bisecting the passageway of the socket member so as to form a stop facilitating frictional mounting of the cross arm unit of the top of a post. When the post is of standard metal construction, the socket member will be arranged so that the arm member crosses its passageway diagonally. When the cross arm unit is intended for mounting on a wooden stake, the socket member will be arranged so that the cross arm member is normal to one set of side faces of the socket member but parallel to the other set. If the cross arm unit is intended to be mounted not at the top but along the length of a post, the socket member can be disposed to one side of the cross arm member. If the arm is of substantial length, bridging elements may be employed. The invention also contemplates a trellis unit which comprises a cross arm unit as above described mounted on a metal stake of standard construction.
