I received this as a gift for guests when I stayed at the Hyatt Regency Hotel in Hawaii last month. It does not have heat or cold retention properties. I only used it once during my stay, so it's clean. I have washed it with hot water, but please refrain from purchasing if you are concerned. You can only get this if you stay at this hotel. I also have two more in different colors, so if you would like to purchase them together, please comment. 1 for 780 yen 2 for 1300 yen