This is Udon, the nickname for the tube workshop "Yukari." Simply attach it under the thumb rest to widen the hand when gripping the lower tube, reducing strain on the right hand. Recommended for those suffering from tenosynovitis or those who want to improve their fingering. I purchased it about a year ago. Retail price: 3850 yen Double-sided tape for attaching it to the tube is not included, so please prepare your own.