Ultrasonic hand tool-for larger area plastics welding: DAWE Instruments Ltd Machinery Llyod (December 1969) p 63 The tool briefly described weighs 4kg and is designed to be hand held: it is applied directly to the joint to be welded and is therefore well suited to welding thermoplastics over large joint areas, as in plastic wall panels, furniture, car bodies and boats. The operating frequency is 20KHz. The typenumbers are: 7025A (for the tool), 1133B (for the power units) (2114)