3 Day Expandable Backpack( With waist pack)   Description:   l Constructed of 600 denier polyester with vinyl backing l Large expandable main packing compartment l Organizer pocket l Side parachute clasps l Easy grip zipper pulls l Back support belt with parachute clasps l Whether it’s a long hike, an overnight trip, or a weekend getaway, the Expandable Backpack will fit your needs l Extra-large, expandable main packing compartment l Easy-grip zipper pulls l Back support belt   Size: 20 1/2″ x 15″ x 7 3/4″ – 12 3/4″ WHEN FULLY EXTENDED Volume: 3920 cubic inches  Weight：3 lbs