Nalgene OTF On The Fly Bottle Features Leak-proof closure Fits in cup holders Fits in bike cages One handed operation BPA Free All plastic bottles and containers are not alike. Nalgene gives you that extra measure of security not available with other containers. Made with super-tough materials, Nalgene closures have no liner that can wear, crease, leak or cause contamination. The container walls are generally thicker and more split and puncture-resistant than lower quality bottles. Guaranteed leak-proof, they consistently keep your contents fresh and provide added protection against leakage and breakage.