?100% Waterproof ? The certified material and the air-tight zipper make the Piscifun backpack 100% waterproof. The waterproof phone case will give extra protection to your phone ?Floating & Lightweight ? The weight of TPU backpack is 70% off the same volume of PVC bag. The one-way air holes can easily inflate the backpack and increase buoyancy(This is not an approved PFD) ?Durable & Stable ? The TPU material is more durable that it would not crack even in the temperature range from -40 to 158? ?Environmental Material? The environmental TPU material is odorless and easy to degrade ?Comfortable Carrying System ?To improve comfort, Piscifun backpack included breathable padded back, detachable waist belt, adjustable chest strap and multifunctional lanyard