Drinking system Naturehike the top, which is fully opened, it is easy to fill with water and can be washed without problems. The elastic drinking tube is very strong and flexible, treated with a special antibacterial coating. Ideal for sports, outdoor activities. The design is completely airtight, the neck is narrow. The design is completely sealed, the neck is narrow. Ideal for sports, outdoor activities. The elastic drinking tube is very strong and flexible, treated with a special antibacterial coating. Naturehike hydration pack