Pulsed electromagnetic field (PEMF) products use a portable magnetic coil or pad which emits specially formulated low-frequency magnetic impulses. The theory is that these pulses help normalize the body's own bio-electrical system, thus promoting health.
A 2009 meta-analysis found that, "Pulsed electromagnetic fields improve clinical scores and function in patients with osteoarthritis of the knee and should be considered as adjuvant therapies in their management."
Pulsed electromagnetic field (PEMF) technology is incorporated into some pet jackets.