I use the one liter size for hiking, backpacking, paddling, and camping. It is a simular size to the one liter Nalgene bottles so it fits in the water bottle parkas that I used with them. It has the best designed lid out there. It is an easy to open wide mouth design with a nice tether. A well designed sip-it lid also comes included with it. It's made with 304 (18/8) stainless steel like the Klean Kanteens but feels a bit sturdier. I'm not sure if it's a heavier guage steel or if it's the dog bone shap that gives it more structual integrity, or both. Fill it with ice & water, put it in a water bottle parka and you'll still have ice cold water at the end of the day. Without a water bottle parka or other insulation, it will sweat like crazy with something cold inside it. But so will any other uninsulated bottle. This one goes to the top of the heap.