NANUK 935 Wheeled Waterproof First Aid Box - IP67 Rated (Empty, Red)Automatic Pressure Release Valve NANUK cases feature an integrated auto pressure valve that equalizes atmospheric pressure changes caused by altitude, temperature, humidity, or location. The micro vent allows air to pass while keeping water out, preventing vacuum lock, and ensuring easy opening. Design & Colors Sleek rounded corners, chamfered edges, and strong character lines give NANUK cases a modern, durable look. Users can select from up to nine