evo.com | Osprey Hydration Packs > The Osprey Seral 4 Hydration Waist Pack is a hip pack for riders who want to travel light without leaving anything important behind. The 1.5L reservoir and 4 liters of storage have you covered for sips, snacks, and supplies, with a low-profile fit to keep it out of the way when things get technical. Less pack, more fun. Main Compartment Internal Tool Organization Reservoir Included A dedicated hydration compartment stores an included Hydraulics(TM) LT 1.5 L Lumbar Reservoir for short to medium rides and compresses for stable carry. 4.5" x 12.5" x 7.5" / 11.5 x 32 x 19 cm AirScape(TM) Lumbar Backpanel Extra-thick ridged foam with center air channel for excellent ventilation. Main bluesign(R) approved, 600D PET packcloth, DWR treatment made without PFAS | Osprey Seral 4 Hydration Waist Pack 2026 in Gray