0°F - 25°F
This is the temperature range where warmth becomes more about survival than comfort. Insulation pieces are the most crucial additions as they trap the heat in making the below freezing temps tolerable. Super Down Pro Jacket and Pant would be a good place to start, and you will most likely need more. Heat retention is the number one priority with this layering system, and with new innovative fabric technology, you can achieve the amount of warmth you need without feeling bulky.