High-quality materials: The inner layer of this water bag is made of PE material, and the outer layer is made of EVA material, which is wear-resistant, anti-corrosion, BPA-free, odorless, non-toxic, and safe to drink. Leak-proof design: The inner liner of the water tank has passed the air pressure test and is completely pressure-resistant. The double-sealed side technology greatly improves durability. It automatically closes when the tube is removed, and the 2-liter water tank will remain full of water without leaking. Large opening, easy to fill and clean: The wide opening is large enough for your hands to clean the water bag, making it easy to fill water and add ice cubes. The large opening allows you to reach the inner corners to thoroughly clean the water bag. 2L Large Capacity: This water bag has a capacity of 2 liters. It is the best choice for outdoor sports, enough for hiking, cycling, climbing, running or cycling for a day of drinking. The size is 40 x 17 cm. Perfect for water bag backpacks: Compatible with most water bag backpacks, just fill with fresh water and put in the backpack. To rehydrate, gently bite the valve and sip like a straw. Suitable for various outdoor activities such as hiking, cycling, marathon, camping, mountaineering, running, skiing, jogging.