I used the largest rubber pad and the sound improved greatly. I ordered a large and it felt like small. Will be returning and getting a new one never opened and sealed for the same price elsewhere. He wears 12. I get a lot of compliments on them and they support my extremely high arch very well which is usually my biggest problem with any sandal. Con: battery sucking, BUT, this will happen with all direct connect units so to me is a non-issue and to be expected. but over all product is very comfortable and good quality . This was easy to assemble however, it is not worth even assembling! I?m super disappointed because I was searching for cute white sneakers for the past couple of months. La misura corrisponde al numero del piede.