Impulse 20Impulse is a versatile companion for a wide range of ambitious day tours, from all day trail runs to alpine mountaineering and day hiking. The zippered main compartment opens wide at the top for easy access to clothing and larger items. Inside are four mesh pockets: one zippered pocket at the top, one pouch on each side of the bottom and a hydration pouch along the foam back. Tube ports on each side and elastic keepers on each shoulder strap