An innovative, ultra-light, efficient system for fast-and-light day hikes and long treks, the PackFlask™ puts hydration right where you want it. Securely attach it to your pack harness for hands-free use. A stretch mesh pouch secures the bottle and — without the flask — carries a phone, snacks, or map. The bottle is light, designed to ride comfortably, and collapses when empty for easy packing. Its leakproof self-sealing nozzle delivers high-flow hydration, and a dust cover keeps it clean.HydraPak Packflask Kit 500ml Features: Stretch Mesh Pouch attaches to your pack harness and securely holds the bottle for hands-free hydration Attach it to most 42mm threaded water filters to create a packable squeeze system. Sized for easy integration with the pouch, the empty PackFlask™ bottle packs small — just flatten, roll, and stash it away. Dust Cover protects the nozzle from dust, mud, dirty hands and bacteria. Quickly opens and closes with a single-handed flip. Lighter than traditional bottles, and made of durable TPU with RF-welded seams. Plugs into filter valve and threads onto a bottle of clean water for backflushing the filter to restore flow rate. Filtration: 28mm filter kit compatible Capacity: 500 ml Weight: 79 g Dimensions: 220 mm x 85 mm  Material: TPU, PP, Silicone, POM, TPE, Polyester, EVA, Nylon