I'm constantly astounded that all you guys don't bother to read the fine print. Geez!
It only works in the Southern hemisphere, and then only if you are taking massive doses of Ibuprofen. A not very scientific study shows that is seems to work better in odd months, except for December. Also, the double stitched garment works better than the single stitched, because the stitching thread is 24% copper. That leaves out the T-shirts, but go double on everything else.