YESO Water-resistant Outdoor Cycling Laptop Backpacks - Large Capacity Sport Travel Hiking Camping Bags 100-percent-cotton-jersey Imported high-density waterproof fabric with super strong Water-resistant. High-quality reflective band can highly reflect vehicle lamps beyond 50 meters; offer you the best safety protection when riding at night High-quality plastic buckle waistband securely locks the loading position, making you carry more easily Equipped with rain cover with special silver coated fabrics, making you even cooler Small:High 18.9 inch, wide 11.0 inch ,thick 7.1 inch,About 1150g. Large: High 20.1 inch, wide 12.6 inch ,thick 7.1 inch, About 1250g.