The North Face Boys' ThermoBall Insulated Full-Zip Jacket has the same look and feel as a down puffy, but it isn't down inside, and that makes a world of difference. ThermoBall insulation mimics the light loftiness of down feathers, but since it's a synthetic, it stays warm even when it gets wet. This makes a considerable difference when you're living in damp, moist, humid environments. The North Face made the shell out of WindWall fabric to block brisk breezes that often accompany winter's snowy weather.