HydraPak HydraFusion Tube is designed with durable and lightweight built-in foam insulation to keep your water cooler in the hottest of temperatures. The insulated hydration tube has a high-flow Blaster bite valve that self-seals after each sip and offers a twist-on-off bar to stop leaks when not in use. The dust cover protects the silicone bite valve so that you don't get a mouth full of dirt.