These large backpacks are made from recycled PET bottles, the lining is waterproof nylon. The zipper is from YKK. On the inside you'll find an elastic bottle holder and a pocket all over the back that closes with velcro. It has adjustable shoulder handles up to 67 cm / 26.4 in. You can easily clean this bag with a wet cloth. Little Wares Thoughts: We love these large backpacks for our older littles (5+). They make perfect school backpacks or can easily store your things for an overnight trip. They are made from recycled bottles and are waterproof so they won't be ruined by a spill and are easily cleaned. For your younger littles, try our Small Backpacks.