Also, it is very nicely made and solid. maybe read the instructions? I found the rack to be amazing for the cost. Nada que ver la numeración, espero puedan hacerme un cambio. ""This has a removable rechargeable battery. they have seen the same amount of use, and work just like the day I bought them. Other than being corded rather than bluetooth, can think of nothing else to share other than the flat foldability is perfect for storage. However, they are a little bit difficult to put on. I have a wide oval shaped bar, and they still worked fine but were a little difficult to get them to not want to sit crooked. I thought I would write a review simply because I really like these and would recommend. The ?UC? version just means that it comes with a little USB receiver/transmitter (BT600) that plugs into your computer.