Lutron EMF-822A: AC Magnetic Field EMF Tester
Rugged, Compact, & Lightweight Magnetic Field Meter
Couldn't be easier to use, just turn it on and get accurate reliable readings. Perfect for situations needing high resolution measurements of AC magnetic fields without spending a lot of money. Large LCD display reads 0.1 -199.9 mG over the ELF range of 30 - 400 Hz. Provides readout in both mG and microTesla. Calibrated to within 4% ±3 digits at 50/60 Hz. This single axis meter samples every 0.4 seconds when flipped on with slide switch. Requires one 9V battery. One year limited warranty.
Like all single axis meters, this meter must be rotated during use to find the proper orientation to the magnetic field being measured to get proper readings.
Please note: this product is intended to measure electric fields, and does not detect nuclear radiation.