I purchased this product on 8/1/08 and on 9/8/08 I plugged it in for the renewable feature. It is more than I expected from a wireless, stand alone product. I use one in each of my walk-in closets and they seem to have taken care of the humidity problem and resulting mold on shoes, etc.As I said, this product lasted for five weeks before I had to 'recharge' it and I am most happy with its performance.