Boring water bottle, right? Wrong.
The Wooly Mammoth is a double walled bottle with Prima-Loft insulation inside. Now, I don't much care about keeping liquids cold longer, but I do love the ability to put warm water in the bottle and not have it freeze in the Colorado mountain winters.
Hydrapak Wooly Mammoth: http://goo.gl/PnzI1
More Gear Reviews: http://goo.gl/crJZL