Dual Hole Car Spark Plug Tester 12V Gasoline Ignition Diagnostic Detector Tool

ANCEL Car Spark Plug Tester Dual Hole Petrol Ignition Analyzer Diagnostic Tool. Place the Spark Plug into tester hole 1 or 2; If you want to compare the new spark plug and old one, place new spark plug into hole 1 and the old on into hole 2.