Ergodyne Chill-Its 5156 Premium Low Profile Hydration Pack, 3 Liter, Black Nylon DURABLE made of 600D water-resistant rip stop polyester with breakaway straps for added safety and security COMFORTABLE vented shoulder straps with 8mm EVA foam padding makes it comfortable all day long. ADDITIONAL STORAGE one zippered compartment with headphone jack, multiple d rings, and nylon webbing. The perfect balance between low-profile and cargo needs. INSULATED PACK AND TUBE keeps water cool and tasting fresh ANTIMICROBIAL bite valve to keep contaminants away and a dual cap bladder for easy ice and water (re)filling. 3.0 LITERS or 101oz of water capacity. Good for approx. 3.3 hours of hydration!