Description: 【Rotation Direction Test】: The Solenoid Tester can help you easily determine the rotation direction of the pump, ensuring accurate and efficient operation 【Alternating Current Magnetic Field Detection】: When expose to a strong enough magnetic field, the Solenoid Test Tool will indicate the presence of an alternating magnetic field by rotating its disc, helping you identify electromagnetic activity 【Function】: The Solenoid Tester is an electromagnetic tool for detecting alternating current fields and a rotation tester for circulating pump, making it a versatile addition to your toolkit kit 【Portable and practical design】: Designed for plumbers, this professional electromagnetic test tool is a must have for your diagnostics and repairs at any time 【Reliable material】: Made of plastic, Electromagnet Testing Equipment is compact and lightweight, can withstand daily use, and is easy to carry Specification: Material: Plastic Size Chart: 4.07 cm/1.60 inch  Package Includes: 1x Solenoid Tester Note: Please allow slightly errors 1-2cm/0.39-0.79inch differences due to manual measurement.