True to size and the only Nike sneakers that don’t hurt my feet so I bought 3 pairs since for whatever reason they discontinued them. Its thick so actually supports and does just stretch with my fat. I bought this for my husbands sneakers. I find this whole system ridiculous because there is no easy way to replace these batteries. The sound seems fine, but I havent really tested that very much, since I cant make the mic work. Bought 2 and they fit my 2 year old and 6 year old perfectly and they are of great quality! Ill be keeping and wearing them until then. Arrived very promptly. The button has a sharp ridge to the plastic and makes it a bit uncomfortable. Despite that, I do like other aspects of this slipper.