Klean Kanteen went back to the drawing board and spent a year developing a new super high-flow sport cap that barely requires any pressure, the Sport . If the old sport cap was a tiny, trickling creek, the new Sport is Niagara Falls. You can actually chug water from it. Really, We've tried the other sport caps out there. And with all due respect, Klean Kanteen's revolutionary Sport gets bragging rights. With 3x the flow of our first sport cap and a quieter valve, the Sport is simply the best sport cap in the metal bottle market. It's also made to last, just like the Klean Kanteen bottles. Made from BPA-free polypropylene, Klean Kanteen designed it with one, simple moving part so it won't break or get crud in the works.