A safety device for use with a load-carrying vehicle, which includes a lamp and a flag to warn vehicles of overhanging or extended loads. The device has a supporting member for attaching to a load. The supporting member may attach to the load using screws, bungee cords, or magnetism, or by receiving the end of a pipe or tubing in an internal indentation. The supporting member is formed as a clamp with two elongate parts hingedly connected in a base unit with a spring mechanism.