1. How it works: Snap one end of the grounding wire onto the continuity tester and plug the other end into a grounded outlet. Then, place the continuity tester on the grounded product and press the button. If the indicator light remains green when you move the tester over the surface of the grounded product, it means that the grounding is successful and continuity is achieved. Please make sure that the grounded product being tested is also plugged into a grounded outlet, otherwise the continuity test will not be possible. 2. What's Included: Our ground continuity tester includes a tester without batteries and a 15-foot grounding wire, which allows you to properly test continuity and can be used as a spare or replacement grounding wire for grounded/earthed products. 3. Safety Precautions - Please read the following precautions carefully before using this detector. Be sure to keep these instructions for future reference. 4. Warning - This is not suitable for use under 8 years old. Contains small parts, do not swallow.