though not as scientific as I would like. My husband and I took the bottles to a football game(being the dutiful band parents of a cymbal player). I did measure the ice and water for equal results. After an hour the Polar bottle had more ice and was cooler. After 2 hours the ice was gone in both bottles. Over night though the Maxchill bottle stayed cooler. Variables include high humidity, mid 90s to upper 70s for the temp.

I'm going to repeat the test at home this weekend. I'll let you know. BTW, this Maxchill bottle didn't have the funky smell.

Donna