Features1. The dual-hole car spark plug tester has two test holes, allowing you to test two spark plugs simultaneously. This enables comparison testing for accurate diagnosis of spark plug performance.2. Tests spark plug performance and ignition strength, compatible with 12V gasoline vehicle spark plugs.3. Adjustable dual-hole spark plug tester for analyzing and diagnosing spark plug operation.4. Purpose: To evaluate spark plug performance and ignition system strength.5. Application: Designed for use with 12V gasoline engine vehicles.User Manual:1. Insert the spark plug into test hole 1 or 2. For comparison, place a new spark plug in hole 1 and the used one in hole 2.2. Connect the tester to a power source.3. Turn the key switch clockwise to power on the device. The indicator light will illuminate, indicating the tester is operating at 1000 RPM.4. Continue turning the key switch clockwise to adjust the operating frequency from 1000 to 6000 RPM. Higher RPM settings produce stronger spark intensity.SpecificationsMaterial: ABSColor: BlackDimensions: 16.5 x 10.5 x 7 cmWeight: 200 gPackage Includes:1 x Spark Plug Tester1 x Power Adapter