Length: 115mm / 4.53in ; Diameter: 22mm / 0.87in ; Cable Length: 520mm / 20.47in; Weight: 96g / 3.39in Perfect diagnostic tool for accurately identifying a weak spark in minutes, simple to use, test for no-start conditions It is the resistance to spark 10k, 20k, 30k and 40k ohms, white lettering can make you read the measurement easier Groud the clip to the engine. Put the other end in the spark plug wire. Read the length on the spark through the little window. The longer the spark the stronger the coil The standard plug wire tip and can be unscrewed so the tester can be used on small engines and some motorcycles. According to spark color and flash over distance to determine the quality of the coil. Can intuitively convenient to understand the operation of the ignition coil. Alligator clip securely fastens to ground. Screw assembly adjusts spark quickly and easily. Avoid fire, the ignition coil burned out and so on. Color: Black Material: Metal+Plastic Package Contents: 1 * Adjustable Ignition Coil Tester Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.