Prototype CAT J-1708 reader made for Mack Trucks. This is from the early days of collecting electronic data from an engine. The part name reads XXX-XXXX-XX. Excellent piece for the CAT or Mack collector that has almost everything. Measures about 7” long. Box has a label from Mannesmann Kienzle that reads Geraet (Device in German) NR. 1554.