The advantage of a magnetic field detector is its ability to measure the strength of magnetic field, which is essential in many applications. With reasonable design and high adaptability, this magnetic field detector can be well applied to identify devices that produce high levels of radiation, and it will be a good choice for you. Features -Color:Black -Material:ABS -Size:15.00X5.50X3.00cm/5.89X2.16X1.18in -Power supply: 1 X 9V battery (not included) -There are 5 LEDs, each representing a field strength range as follows: Dark Green - "normal" area - normal background magnetic field. 0 to 1.5 Green - "low" zone - low level magnetic field. 1.5 to 2.5 Yellow - "Warning" area - medium magnetic field. 2.5 to 10 Orange - "high" zone - high magnetic field. 10 to 20 Red - "Warning" zone - extremely high magnetic field. 20+ - Keep you from magnetic field, good for your health. Lets you detect radiation anytime, anywhere. - One hand operation, one touch to detect electromagnetic magnetic field level of home appliance. - Special features: 5-led indicators, representing different magnetic field values, easy to use. - Suitable for computer, hair dryer, microwave oven, water kettle, fridge, laptop, TV, and etc. - Adoption of simple and convenient design, this product also can be used for a long time. Package list: 4 x meter