Automotive Spark Plug Tester & Ignition Coil Analyzer - Dual Hole, 500-9000 RPM,

Dual Hole Spark Plug Tester: The Ultimate Tool for Efficient Diagnostics. Why Choose a Dual Hole Spark Plug Tester?. Adjustable Working Frequency: Features a knob that allows you to adjust the working frequency from 500 to 9000 RPM.