Vinylon F fabric has been used in Kånken day packs for the past 25 years. While being a synthetic fibre, Vinylon F still maintains the properties of natural fibres. Most conventional backpacks need a coating to become water resistant. This provides a short term waterproofing but loses its properties over time. Vinylon F needs no extra coating and absorbs moisture better than any other synthetic fibre. It swells like a natural fibre making the weave more dense when wet. This gives waterproof qualities eliminating the need for coating.