LIGHTWEIGHT & COMPRESSIBLE: 50% lighter than a hard bottle and compresses down to pocket size when empty. HIGH FLOW NOZZLE: High flow drink nozzle includes protective dust cover and can be quickly opened and closed with one hand. FILTER COMPATIBLE: Compatible with 42mm threaded backcountry water filters including the HydraPak 42mm Filter Cap. FITS IN PACK POCKETS: Designed to fit in pack pockets when full and to roll up when empty for space saving storage. ULTRA DURABLE: Made of dual-layer film laminate construction, with abrasion resistant TPU & RF welded seams for superior durability and elasticity.