Description:  Length: 115mm / 4.53in ; Diameter: 22mm / 0.87in ; Cable Length: 520mm / 20.47in; Color: Black ; 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 gap 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 gap 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.    Features:  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 gap quickly and easily.  Avoid fire, the ignition coil burned out and so on.    Specification:  Length: 115mm / 4.53in  Diameter: 22mm / 0.87in  Cable Length: 520mm / 20.47in  Color: Black  Weight: 96g / 3.39in    Package Weight : 96 G / 3.39 Ounces  Package Dimensions (L*W*H) : 190*75*25 MM / 7.48*2.95*0.98 Inches    Package Include:  1 x Adjustable Ignition Coil Tester