Carburetor Adjustment Tool kit for Echo Poulan Husqvarna MTD Ryobi Must have for 2 Cycle engines to keep them in good performance: Package include: 12 carburetor adjustment tools, Carburetor tool case, Ignition Coil Spark TesterCan be used on ZAMA, Walbro, Ruixing, Huayi, STIHL, Husqvarna, Poulan, Sears, Craftsman Echo, Homelite, Ryobi, MTD, Troy-Bilt, Cub Cadet, Toro, Sears.string trimmer, chainsaw, leaf blower, hedge trimmer, edger, pole pruner weedeater and other machines that utilizes the carburetor adjustment tool. Ignition Coil Spark Tester: It is the quickest way to test for no-start conditions, test if the spark plug is getting the spark and to see how strong it is.Can be used on all kinds of engine which equipped with ignition coil. Car, motorcycle, 2-cycle small engines trimmer / chainsaw... 4-cycle engines lawn mower / tractor, etc.High visibility white lettering makes it easy to read the gap measurement from 0 to 40kStandard plug wire tip and can be unscrewed so the tester can be used on small engines and some motorcyclesAdded a spring to the tightening bolt which keeps secure and stays where you put it Carburetor Adjustment Tool Kit 12 Screwdrivers for Common 2 Cycle Small Engine How does this connect to a coil on plug system? Grip 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. Specifications: SE means small engine that puts out less spark.20 is .020 inches30 is .030 inches.40 is .040 inchesCheck your engine manual which may tell you what your engine is supposed to put out