Features:A professional tester for identifying the polarity of magnetic field fastly and safely.Pen type magnetic tester, mini and portable.One button operation, easy to use.The north and south polarity can be distinguished by the two signal lamps(red = N pole, green = S pole).Comes with a sturdy plastic tool case.It can be used for the determination and identification of permanent and electromagnet poles, magnetization polarity check, and coil test.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 * 0.94inItem Weight: 64g / 2.27ozPackage Weight: 263g / 9.30ozPackage Size: 22 * 10.5 * 5.7cm / 8.66 * 4.13 * 2.24inPacking List:1 * Tester1 * Storage Case1 * Manual (English)