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 resistance to spark 10k, 20k, 30k and 40k ohms, white lettering can make you read measurement easier Groud clip to engine. Put other end in spark plug wire. Read length on spark through little window. The longer spark the stronger coil The standard plug wire tip and can be unscrewed so tester can be used on small engines and some motorcycles. According to spark color and flash over distance to determine quality of coil. Can intuitively convenient to understand operation of 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 above package content, other products are not included. Note: Light reflection and different displays may cause color of item in picture a little different from real thing. The measurement allowed error is +/- 1-3cm.