Great bottle -- clean taste, durable
I have about 5 of these bottles now and have completely replaced my Nalgene (and similar plastics) for all of my hiking and backpacking needs.
The Klean Kanteen bottles are all stainless steel which provides a lightweight but durable bottle that yields great tasting water all the time.
Note: these are NOT thermos bottles so cold water won't stay cold (although I have no trouble loading ice into the opening of these bottles) and I would HIGHLY recommend that you NOT put hot liquids inside as you'll easily burn yourself with the bottle.
The caps are all interchangeable as ever KK bottle has the same opening dimensions.