One of the key features of this magnetic field can be to detect magnetic field that are not visible, allowing it to be used in areas where visibility is . Mainly used for testing TV, computer, microwave oven, low-frequency home appliances, EMF tester, etc. 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+ - The EMF tester tool helps measure electromagnetic fields to identify radiation for you. - The magnetic field is an electronic device that measures the strength of electromagnetic fields. - The emf meter enables users to determine the extent to which to exposure, both useful and practical for home use. - Magnetic field is a portable tool for magnetic field that cannot be seen or touched, an essential tool for many industries. - The emf meter can be applied for testing TV, microwave oven, refrigerator, computer, towers, etc. Package list: 3 x meter