15.6‘’ travel backpack: Product Dimensions: 17 x 12.5 x 6 inches; Item Weight: 1.9 pounds; Normal Capacity: 30L; Fit up to 15.6 inch laptop; Material: Water-Repellent and Durable Nylon Fabric; 17‘’ travel backpack: Product Dimensions: 20 x 13 x 8 inches; Item Weight: 2.2 pounds; Normal Capacity: 40L; Fit up to 17 inch laptop; Material: Water-Repellent and Durable Nylon Fabric; 18‘’ travel backpack: Product Dimensions: 21 x 13.5 x 8.5 inches; Item Weight: 2.3 pounds; Normal Capacity: 45L; Fit up to 18.4 inch laptop; Material: Water-Repellent and Durable Nylon Fabric;