I've got dozens of Nalgene, a couple Klean Kanteens, and 2 Hydroflasks. The hospital I work in doesn't have water fountains, and says staff can't drink the bottled water they provide for the pts. censored:, I know, and followed by few, but I'm a hard ) Anyways, I've carried all of these, even a few Platypus', and a soft sided Nalgene. (Don't ever waste your money on the soft sided Nalgene! I bought 2, and both didn't last a week each before they started to leak at the welds. Anyway, I carried a 40oz KK for about 3 years, and retired it for the 40oz HF. In winter, I can put 10 ice cubes in it prior to filling, and I'll have ice left over after 12 hours. I rarely drink more than 1 filling in that time during the winter. In summer, I up to 15 cubes, and even after a refill, I'll still have ice after 16 hours at work. I like cold water, the colder the better! I have one of those cold immunities, so even in winter, when I sweat lees, I'm still hot, I just drink less. I'll drink room temp water, but I much prefer it icy. This is where the HF excels. When I carried the 40oz KK, I had the LL bean neoprene cover, which did help in the ice department, but LL no longer sells the neoprene cover, and when mine wore out, I had to do something different. This is where the HF came into play.