Winter Snow Bib Pants. 2-Layer, 20k waterproof shell bibs. Technical, versatile, and the extra coverage of bibs. The women's Burton Reserve 2L Bib Pants are the shell pants you can build your winter layering system around. Fully-taped seams and two-layer 20k/20k storm protection make for a warm, dry world when paired with the base layer of your choice. A complete package of rider-designed features gives you all the venting, adjustability, and functional pockets you need to dial in your comfort on the mountain