The GTX offers a number of special features compared to the GT-series and the previous GTO-series. It is equipped with an aerodynamic dome to help airflow and to give extra water protection. Waist belt attachments are made from of steel and not plastic. The biggest change compared with the GTO-series is the back panel which is now made from a single piece of ergonomically molded soft-foam. This improved ventilation and breathability as well as increased shock absorption. Impact protective ABS shell Back protector CE label-level 2 Aero dynamic top cover with pocket Safety lock - aluminum / nylon 15" laptop compartment / or hydration Max. Laptop Size: 15in x 10 in x 2 in Reflective 3M - traffic comp. EN 471 Dimensions: 22 in x 12 in x 6 in Weight: 4 Lbs Volume: 1220 cu in - 1525 cu in / 20 Liters - 25 Liters