Flexible, TPU Materials - Durable construction that is soft and flexible for easy squeezing. Small and Packable - Compact and collapsible, so you can stash in packs, belts or vests. High-Flow Self-Sealing Nozzle - Easy to drink on the move, without any leaking. Locking Cap - Open and close using your thumb, preventing leaks and messes. Two Pack - Carry essential hydration on your run.