1. Material: The waterproof dry bag is made of PVC semi permeable waterproof fabric, designed specifically for years of use. The material is sturdy and has a long service life. Perfect for any extreme adventure you can imagine. 2. Convenient Shoulder Strap: These dry bags have adjustable one-shoulder straps which provide safety and stability while wearing the bag. These sturdy straps help the bags in not slipping off the shoulders during the water activities. 3. How to Use: Align the straps on the top of the waterproof dry backpack after stores your gear, then grab and roll the straps 3-4 times and connect each side buckle of the dry sack backpack to complete the seal. Stretch two side straps to protect the bag from leaks. Connect the top buckle and stretch the strap to avoid getting your gear wet. Each backpack dry bag is equipped with a wide firm hand-hold for your convenience, meets your different demands for handheld or shoulder carrying. 4. Sizes:10L-dark blue,to choose, a right choice of gift for women and men. Bringing comprehensive protection for your safe travel. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.