Light but tough material that is the outer layer of bark of a cork oak. It is an excellent thermal ( 0.037 W/mK) and acoustic insulation. It also has a very high specific heat capacity, and therefore high thermal inertia. It is impermeable, a fire retardant and highly abrasion-resistant. It is highly resistant to moisture and UV radiation, and can be left exposed on an outdoor facade. It is 100% biodegradable.