While not a strict debunking of the exact device you link to, I found this interesting write up at JREF. I think the quackwatch link may provide you with additional information.
How to Debunk Biomagnet Therapy in Less Than a Minute
Written by Brandon Peterson
Wednesday, 17 March 2010 10:32
I recently had the opportunity to attend The Amaz!ng Adventure 5. While at Grand Turks, our final port, I was wandering through the duty-free shop looking for deals on liquor (Jack Daniel’s Single Barrel for $39!) when I happened upon a tableful of woo. Seeing as I was a medical student on a skeptical cruise, I had to stop and have my wife help make this video.
In my off-the-cuff video, I didn’t have the opportunity to mention the lack of scientific evidence for their claims. Even if the magnetic field did penetrate the skin, it still would not stimulate blood flow because the amount of iron in blood is far too small. If blood did have a strong magnetic attraction, your body would explode in an MRI (which would be cool, I admit).
I also didn’t have time to discuss the clinical trials that have been performed to evaluate efficacy. As usual with CAM research, earlier poor quality studies were weakly positive (1,2), while more recent high quality studies and meta-analyses are definitively negative (3,4,5).
I also forgot to mention the numerous court rulings in the late ‘90s and early ‘00s against companies making false claims about these products. This issue is discussed extensively on Quackwatch for those interested (6). In a nutshell, companies that fraudulently claimed to treat specific illnesses (arthritis, diabetic neuropathy, migraines, etc.) were sued. Now, they use nebulous phrases such as “support the healing process” or “restore natural energy.” You know, phrases that have not been evaluated by the Federal Drug Administration and are not designed to diagnose, treat or blah blah blah.
In short, magnet therapy is a great case study of CAM. The lack of scientific plausibility, the progression of the medical literature, and the FDA Miranda Rights statement are all characteristic of CAM. And if a lowly medical student can debunk it is less than a minute, how good can it really be?
Harlow T, Greaves C, White A, et al. Randomised controlled trial of magnetic bracelets for relieving pain in osteoarthritis of the hip and knee. BMJ 2004; 329:1450-1454
Vallbona C, Hazelwood CF, Jurida G. Response of pain to static magnetic fields in postpolio patients: A double-blind pilot study. Archives of Physical and Rehabilitative Medicine 1997; 78:1200-1203.
Winemiller MH and others. Effect of magnetic vs sham-magnetic insoles on plantar heel pain: a randomized controlled trial. JAMA2003; 290:1474-1478.
Pittler MH. Static magnets for reducing pain: systematic review and meta-analysis of randomized trials. CMAJ 2007; 177(7): 736-42.
Cepeda MS, Carr DB, Sarquis T, et al. Static magnetic therapy does not decrease pain or opioid requirements: a randomized double blind trial. Anesth Analg 2007; 104. 290-294.
Barrett S. Magnet therapy: a skeptical view. Accessed March 15, 2010. Available at http://www.quackwatch.org/04ConsumerEducation/QA/magnet.html
I will note that there are things that electromagnetic fields can do to the human body. In particular the neural effects if placed about the head (see God Helmet). However, the main thing to do when dealing with claims like this is to ask yourself: By what mechanism is this device claiming to work? How does this align with what we know about biology, chemistry, physics, etc.? Does the claimant use language that would be high on the crankpot index?