Klean Kanteen Classic bottles have three different cap styles: Sport 2.0, Loop and Flat. The revolutionary Sport Cap 2.0 effortlessly delivers a high flow rate that makes it easy to drink from your bottle without removing the cap. The Loop Cap is totally leakproof and has a durable attachment point so you can clip it on to just about anything. And the Flat Cap is low-profile, unobtrusive and leakproof.