Size: Each small engine spark tester features 6 1/4" shield/cable, 5" shaft/light cover. Suitable dimension to check compatible for spark in even the hard to reach areas. Material: The spark plug tester is made of quality plated shaft , rust and corrosion resistant, internal bulb lasts compatible for years, clear housing is replaceable. Easy to Use: Turn the engine off and remove the spark plug coil. Connect the black plastic leather connector of the spark plug tester to inline spark plug tester. Connect the metal end of this spark plug tester to the spark plug coil. Start the engine. If the light flashes, the ignition wire is intact. Features: The spark tester probe could quickly and easily diagnose ignition/engine outboard motor issues or a fault in the fuel delivery system, this engine ignition coil tester is a must have compatible for any personal, professional machine store and automotive store. This automotive spark tester is perfect compatible for basic troubleshooting of all internal combustion engines, cars, trucks, motorcycles, lawn mowers, chain saws, trimmers, snow blowers, generators, etc. _x000D_