• Lightweight and comfortable: This backpack weighs only 500 grams. The ergonomic design makes your back more comfortable. The soft, breathable mesh pad on the back keeps the back cool and dry. Adjustable shoulder strap, waist belt and chest strap. • Safety and compartment: This backpack adopts heat insulation design, can hold 2L water bag, and can be water cooled for up to 4 hours. The inner tank is made of EVA environmentally friendly material, which is safe for the body. There is a fixed design up and down to ensure that the bladder will not bounce during the hike. • Design and advantages: The size is 17.5 * 6.7 * 2 inches. The main compartment is spacious enough to accommodate water bags, iPads and lunch boxes, and you can carry clothes with you. More space gives you greater possibilities. • Material and capacity: 2 liters of EVC FREE BLACKDER is made of food grade approved materials. It is leak-proof and can be easily removed through the main pocket. The oversized 2-inch wide screw cap makes the ice cubes cooler to drink and easy to clean. Equipped with a non-kink tube and a soft high-flow bite valve, and with an easy one-hand closing button. • Electrical appliances and gifts: This backpack is a good gift for friends and family who like outdoor sports. This is the best choice for short trips, running, biking, hiking, skiing, camping, hunting.