Hi team chilly. After an initial purchase of two bottles (medium and large) I gave them a serious testing to see if they lived up to your claims.. I left them in my car on the hottest day of the year in full sunshine and high temperatures... Tried one after 12 hours ... Ice cold ! Tried the second one 21 after hours and still ice cold! Test completed I went on to buy a further four bottles. I now have two complete sets (one in Matt black and one in brushed aluminium). They really are excellent and the chilly cleaning brush fits all sizes and gives the bottles a great internal clean. They look great , feel great in your hands and do exactly as you have stated in your claims. Wishing your company continued success ... "Long live the chilly bottle!"