"Power Balance is based on the idea of optimizing the body’s natural energy flow, similar to concepts behind many Eastern philosophies. The hologram in Power Balance is designed to resonate with and respond to the natural energy field of the body." That's the quote from the Power Balance website. The product of which they speak is a rubber bracelet with two mylar holograms on it. The claim is that wearing this thing helps improve balance, strength, and flexibility.
Well MY claim is that this product is a pile of horsecrap. There is absolutely no solid scientific reason why this piece of junk would have any effect other than that of a placebo.
If you have $20 burning a hole in your pocket, do yourself a favor and pick up a couple of these instead.