Designed for riders seeking a sleek lumbar pack with built-in hydration, the 4-liter Seral is the ultimate trail sidekick. With its slim profile and integrated 1.5-liter Hydraulics reservoir featuring a robust magnetic coupling, this waist pack ensures efficient hose management even on rugged terrain. Plus, it offers ample storage for ride essentials like a spare tube, CO2, multi-tool, and snacks. Osprey Seral 4 Features: AirScape backpanel with contoured lumbar wrap for maximum stability Spacious zippered main compartment with reservoir sleeve Includes Osprey Hydraulics 1.5 L Lumbar Reservoir with secure magnetic hip belt bite valve attachment Internal tool organization and zippered pocket in the main compartment Blinker light attachment with reflective graphic for added visibility