Description: Material: Made of 500D mesh cloth and PVC Material, IPX7 waterproof and wear resistant. Large Capacity: Side storage net pocket design beach Bag, backpack closure, waterproof reinforced, buckle strap for hanging outdoor items . How to Use: the straps on the top of the waterproof dry backpack after stores your gear, then grab and roll the straps 3-5 times and connect each side buckle of the dry sack backpack to complete the seal. Easy to Carry: Lightweight design, convenient travel, Comfortable and breathable, there are two ways to switch between shoulders/single shoulders . Widely Used: Suitable for outdoor activities, no matter hiking, camping, climbing, biking, even water sports like floating, kayaking, swimming, rafting, boating, canoeing, fishing, surfing, rowing . Specification: Material: PVC, Mesh Cloth Capacity: 20L, Size: Flat lay 60cm/23.62inch, roll down 46cm/18.11inch, 35.5cm/13.98inch Capacity: 30L, Size: Flat lay 69cm/27.17inch, roll down 54cm/21.26inch, 36cm/14.17inch Package Includes: 1 Piece Waterproof Dry Bag Backpack Note: Conversion: 1inch=2.54cm, 1cm=0.393inch Please allow slightly 0-1cm difference due to manual measurement. Colors can appear different depending on light and how the listing is viewed. Thanks for your understanding and attention. Wish you a pleasant shopping experience!