How to Use: Step 1: Put the items in the bag, grab the black strap on the top of the bag and align the ends of the strap. Step 2: Roll down the top of the bag 3 to 5 times until you feel the air remaining in the bag is suitable; the tighter the roll, the better the waterproof performance. Step 3: Connect the buckle to complete the tight; the buckle and the strap form a natural handle. Specification: Item Type: Waterproof Bag Material: 70D High Tenacity Nylon Waterproof Fabric Product Specifications: 1L, 5L, 10L, 20L, 35L 1L Size: Approx. 16 x 21cm / 6.3 x 8.3in 5L Size: Approx. 21.5 x 43cm / 8.5 x 17.0in 10L Size: Approx. 31.5 x 53cm / 12.4 x 20.9in 20L Size: Approx. 35 x 60cm / 13.8 x 23.6in 35L Size: Approx. 42.5 x 68cm / 16.7 x 26.8in Adjustable Shoulder Strap Total Length Range: Approx. 72-131cm / 28.3-51.6in Package List: 1 x Waterproof Bag 1 x Shoulder Strap