See pics.
Vintage AC Arnold Mfg. Co. Cam-Dwell-Indicator With Instructions
Vintage AC Arnold Mfg Cam Dwell Indicator Auto Test Tool Mechanic Distributor
Vintage AC Arnold Mfg. Co. CAM - DWELL - INDICATOR Tester
Vintage Arnold Mfg. Co Cam Dwell Indicator AC Tester Tool w/Case
