Features: A professional tester for identifying the polarity of magnetic fields quickly and safely. Pen-type magnetic tester, compact and portable. One-button operation, easy to use. North and south polarity can be distinguished by two signal lamps (red = N pole, green = S pole). Includes a durable plastic tool case. Suitable for determining and identifying permanent magnet and electromagnet poles, magnetization polarity checks, and coil testing. Specifications: Material: ABS Sensitivity: +/-5mT (50Gs) Display: 2 LED lights (red = N pole, green = S pole) Operating Temperature: -20°C to 80°C Storage Temperature: -40°C to 150°C Power Supply: 2 x 1.5V AAA battery (not included) Item Size: 154 x 27 x 24mm / 6.06 x 1.06 x 0.94in Item Weight: 64g / 2.27oz Package Weight: 263g / 9.30oz Package Dimensions: 22 x 10.5 x 5.7cm / 8.66 x 4.13 x 2.24in Packing List: 1 x Tester 1 x Storage Case 1 x Manual (English)