Vicki - it is basically just very high frequency sound waves and hence produces vibrations in soft tissues, increasing blood flow and can reduce inflammation. Pentrates about 2 inches deep into tissues.
Ed, I reckon it would be great for tendonitis and any number of painful conditions.....bursitis, fibromylagia etc. I have a friend with plantar fasciitis and another who gets gout pretty bad and am hoping they'll be willing guinea pigs ; ) Probably need the lowest setting on gout

Larry - relatively expensive - but then, no more than a few chiropractic or massage treatments, and yes, can be bought on the market without a prescription.