When we need to take along our tools and snacks on the ride but don't want a full-blown backpack, the USWE Zulo 6L Hydration Pack is one of our top choices. Complete with a cushioned and ventilated backpanel, a dedicated tool compartment, a large main compartment that stores a 1. 5-liter hydration bladder, and an adjustable waist belt, the Zulu 6L can store everything we need for a day out on the trails.