Single axis electromagnetic field measurements (30Hz to 300Hz) The Extech 480823 EMF/ELF meter allows you to measure electromagnetic field radiation levels from fans, electrical appliances, wiring, and power lines. Featuring a large 1/2 in. LCD display and a sampling time of 2.5 times per second, you can be assured of easy and accurate measurements. Readings available in both mill gauss or micro Tesla. Battery included.