The North Face Hyvent is a fabric that has been treated with a polyurethane coating which consists of a tri-component, multi-layer formula. It's been lab tested by The North Face to ensure that it will deliver waterproof functionality, breathability, and long-lasting durability. It works by providing a completely waterproof shell that protects in rain and snow conditions. The North Face Hyvent is also designed to be highly breathable, so it won't smother you with heat despite its barrier-like properties.