Feature:1. A professional tester for identifying the polarity of magnetic field fastly and safely.2. Pen type magnetic tester, mini and portable.3. One button operating, easy to use.4. The north and south polarity can be distinguished by the two indicator lamps(red = N pole, green = S pole).5. It can be used for the determination and identification of permanent and electromagnet poles, magnetization polarity check, and coil test.Specification:Specifications:Material: ABSSensitivity: 5mT (50Gs)Display: 2 LED lights (red = N pole, green = S pole)Service Temperature: -20~80Storage Temperature: -40~150Power Supply: 2 * 1.5V AAA battery(NOT included)Item Size: 154 * 27 * 24mm / 6.06 * 1.06 * 0.94in Item Weight: 64g / 2.27oz.Package List:1 * Tester1 * Manual (English)