ITEM NAME:Spark Plug Tester Ignition System Coil Engine In Line Auto Diagnostic Test Descriptio n Feature: Must-have diagnostic tool for any engine with a spark plug When engine won't start, gives instant answer to 'does it have spark?' Simple to use - just remove rubber boot from spark plug, insert tester & place tester boot on plug Turn the engine over - if ignition is being sent to the cylinder, light in tester glows Great time and frustration-saver with cars, motorcycles, boats, chainsaws, lawn mowers & more Describe: Material: aluminum + plastic Colour: Black Size: length 29.3cm / 11.54" Product List: Spark Plug Tester*1 Test method: 1 Turn off the engine and disassemble the spark plug coil 2 Connect the black tip of the tester to the spark plug 3 connect the metal end of the tester to the spark plug coil 4 start the engine 5 If the ignition wire is intact, the indicator light flashes Notice: 1.Please check the size before.Simple to use - just remove rubber boot from spark plug, insert tester & place tester boot on plug. Must-have diagnostic tool for any engine with a spark plug. Turn the engine over - if ignition is being sent to the cylinder, light in tester glows.