Does NOT perform as promised. Put in cold water and could immediately feel the coldness on the outside of the flask (what insulation?!) & within 2-3 hrs, water was close to room temperature...very very disappointing... EDITING this review because it turns out the 1st one I got was faulty and Amazon quickly refunded me and I got a 2nd (32oz) & (recently) a 3rd 64oz one and they are perfectly fine! Initially wrote to Ironflask but they explained I had to reach out to Amazon for my refund since I bought it off Amazon. All round amazing service from both Ironflask & Amazon.sg. Very happy with my 2 recent purchases. Highly recommend!