100A THYRISTOR FOR WELDING MACHINES. IT'S APPLICABLE FOR OLD VERSION WELDERS SUCH AS KN 40 SMN, KN 41 HB, KN 41 HBS JOYSTICK, KN 67 HBS JOYSTICK, KN 67 HBA JOYSTICK, KN 100 HBA JOYSTICK AND KN 120 HBA JOYSTICK. WHICH HAS OLD VERSION CONTROL BOARDS.