Rugged Twill is exceptionally strong and dense 100% cotton twill. The tightly woven material is finished with a dry-wax treatment that dramatically increases its water resistance and adds further durability. In testing, our Rugged Twill has demonstrated tear strength in excess of 1,400 pounds. It takes specialized equipment to produce this fabric, and our suppliers are England’s oldest and best. While not strictly waterproof, customers have reported their gear staying dry in our Medium Rugged Twill Duffle after sitting several hours in the bottom of a wave-swamped canoe. That level of water resistance assures that devices and files will be safe through any weather in our Original Briefcase. Filson Rugged Twill bags are built with the highest-quality materials and manufacturing to ensure they live up to our legacy of unfailing goods.