Outch -- material is that of a sea through membranous type of material which does not hold or support the foot at all; true, this a comfortable non-supporting shoe, which is hard to walk in because your toes and the front of your feet moves outside of the shoe, there is no structural binding or support built within the shoe that will support and hold the foot inside of the shoe, if it was not for the binding straps, when walking, the shoe will be wrapped around and wearing your ankles instead of holding the feet in place, scary -- will I purchase this item again, no, this shoe is very porous and membranous no support whatsoever, it is a unique shoe and that is all.