Using highly abrasion-resistant 900 Denier nylon with our full-grain leather allows us to build an extremely durable upper. 100% waterproof and breathable, GORE-TEX liners ensure that no water gets in, while allowing sweat and moisture to get out. We use a flexible snake protection fabric in between the liner and exterior of the boot to give you complete snake protection from the bottom of your foot to the top of the boot. The 851 last is an update to our popular 850 last. This last fits true to size with an athletic and supportive fit while providing ample room in the toe. Offering a specific heel shape that locks the heel in place for better fit and comfort on the back end of the boot, this supportive fit is ideal for those needing high mileage performance from their gear.