To answer your question, I did some testing on the King Brand BFST device, specifically the one designed for foot injuries. I purchased the device to hopefully heal Plantar Fasciitis which I have been suffering with for the past four months. I believe that all of the BFST devices are virtually designed electronically similarly, but are physically engineered to address different areas of the body. I am also an electronics engineer, and I do not work for King Brand.
The test was done using just a small coil of wire connected to an oscilloscope. The coil of wire was placed directly on the flexible 'energy web' as King Brand calls it. I started with the 'energy web' unplugged, then connected it to the power controller, then stepped it up through low, medium, and high (1,2,3). Waveforms NOT consistent with 60 HZ (60 cycles per second) household electrical were detected on the scope only when the energy web was connected to the controller, and increased in magnitude as the controller was shifted from position 1 through position 3.
I have seen a few posts saying that the BFST is just a high-priced heating pad. Although it may get warm to the touch, especially on the high setting, it is definitely NOT just a heating pad. According to my tests, the BFST generates a pulsed sinusoidal waveform at about 10 MHz (10 million cycles per second). This is a radio frequency located in the HF (high frequency band). The pulsing rate is at about 200 KHz (200,000 pulses of 10 MHz per second).
I have tried just about everything else for my condition, and today is the first day of using it. I will post again after a few weeks of using it. I am very hopeful that it will work.