COPPERSHIELD and COPPERSHIELD UL are two prefabricated membranes reinforced with a nonwoven fibre glass mat and a blown bitumen and filler blend. COPPERSHIELD is faced with annealed copper foil, which is embossed during the continuous calendering process; while COPPERSHIELD UL is a membrane specifically designed for use as an underlay as it is perfectly compatible and homogeneous with the cap sheet. The specially designed COPPERSHIELD embossed pattern - which is produced with a procedure that allows the metal to expand freely - together with the quality of the carrier of both COPPERSHIELD and COPPERSHIELD UL layers, give ultimate resistance to sudden changes in temperature, even very extensive changes.