An advance: 1 star does not exist for the product, but for customer service by Promed. Because 1 unit had an imbalance and wobbled, 2 device as well. The second device, however, had sent to me without hesitation Promed directly as a substitute after I called. Unfortunately, the replacement had just same Macke, the bits all ran out of round -. Although it was :-( Well, obviously probably not advance allegedly tested by the Customer had the device Promed Ultra Pro advised me to request this I had ordered, and tested. with this I am very satisfied