I have come to the place where I now will only promote FDA Cleared (different than FDA Registered) to health practitioners that are using it in a clinic. I will also not sell high amperage non FDA Cleared foot spas to residential users. I have not had any problem with the lower amperage ionic foot spas that are from China because they are so low powered to start with.
Latest technology in FDA Cleared foot spas
Until now, all foot spas I have reviewed, the arrays produced negative electrons. The newest foot spas have dual modes where they do the opposite and produce positive ions. Most blood poisons are already negatively charged and the way to help neutralize the blood toxins and toxic gasses in the blood is to put positive electrons, and switch back and forth from positive and negative to keep the body neutralized.
FDA cleared (clearance) VS FDA Registered
The cleared ones can be sold and billed as an approved device (FDA Registered foot spas cannot be sold as a Class 2 medical device and cannot made medical claims. FDA cleared are much more expensive because they have been approved. The AMD brand is built to their specifications although the prices reflects it. Theirs is the only Class 2 medical ionic foot bath I have found. See the AMD page here to review their ionic foot spa.