The durable water repellent (DWR) we use to impregnate our Eco-Shell garments is fluorocarbon (PFC) free. This is great news for nature, as PFCs don’t break down, and instead stay in the environment, slowly working their way up the food chain. So by choosing a PFC-free garment you’re choosing to not let these fluorocarbons free into nature. The compromise is that extra care is required to ensure your Eco-Shell garments retain their waterproofness. But the DWR's even more critical ability is retaining the shell garment's breathability. By keeping the outer material dry, moisture inside the garment is "drawn out" to the drier place. It's a matter of physics!