1. Easy and convenient operation: It takes only about 30 seconds to troubleshoot all internal combustion engines. Simply connect the tester between the spark plug and ignition cable. When sparks are generated, the tester reflects the spark and light to identify issues such as dirty spark plugs, defective components, faulty cables, or poor connections. 2. Materials and dimensions: The spark test probe is made of a quality coated shaft, resistant to rust and corrosion. The doublesided flexible tool provides a straight design, and the internal bulb lasts for years. Its compact dimensions allow for spark checks even in hardtoreach areas. 3. Diagnose misfire problems: Ignition failures can cause engine stalling or power loss. The spark plug tester quickly and easily diagnoses ignition and engine issues, including outboard engine problems, fuel supply system faults, spark plug connection errors, contact point defects, and damaged cables. 4. Light indicator: The spark plug light tester detects irregularities and sparks while protecting you from electric current. A bright white light indicates a healthy spark, while a faint color suggests a weak coil or spark plug. Eliminate guesswork with this lawn mower spark plug tester and coil package tester. The tool can be disassembled to access and the internal bulb.