It is made of 80g non-woven fabric and coated with waterproof polypropylene. After putting the item into the backpack, tighten the pull belt to close it. There are 2 pockets on the side to fill.You can use these cinch pouch packs to hold the supplies that you need.Side mesh bag can put water cup, very convenient. The items in the backpack are not susceptible to moisture, which can keep the items clean and dry.