Features:  1. Instantly respond to EMF fluctuations and spikes. Need 9V battery.  2. Easy to read LED lights in the dark and in the sun.  3. Portable, easy to use, rugged, reliable, super responsive.  4. UV reactive color label.  5. Used for ultra-normal wave research and general EMF testing.     Specification:  Material: ABS;  Detection Range: 0 to 20+ milliGauss;  Detection Frequency: 50/60 Hz (50 to 1000 Hz—ELF);  (1000 to 20,000 Hz—VLF);  Accuracy: 5% (typical);  Operating Temperature: 0 ~ 120°F (-18 ~ 49℃);  Battery Requirements: 9 V battery;  Size & Weight—5.75 '(L) x 2.25'(W) x 1'(H); 6 ounces;  Color: Blue/Black.     There are 5 LED's, each represents a field strength range as follows:  Green: 'Normal' zone—Normal background Magnetic Field-0 to 1.5 milliGauss;  Green: 'Low' zone- Low-Level Magnetic Field-1.5 to 2.5 milliGauss;  Yellow: 'Caution' zone-Mid-Level Magnetic Field-2.5 to 10 milliGauss;  Orange: 'high' zone-high-Level Magnetic Field-10 to 20 milliGauss;  Red: 'Warning' zone - Extremely high Magnetic Field-20+milliGauss.     Operation:  1) Hold the EMF METER with your thumb on the switch.  2) Point it toward the EMF source, then depress and hold down the switch (a short flash of the LED's will occur).  3) The LED will indicate the range of the EMF at that level.  4) Moving the device from side to side or rotating it may change the reading; the highest reading is most accurate.  5) Move closer or further away to the EMF source to determine the 'Normal' zone, as indicated by the Green LED.     Helptul Hints:  - Record the readings on the enclosed Exposure Log, repeat periodically, since fields can change in strength.  - If the GREEN LED (Normal) doesn't light, the battery is low.  - To change battery remove the two screws, replace 9V battery.     Package included:  1 x EMF Meter(Not included battery);  1 x English User Manual.