3M(TM) Damping Aluminum Foam Sheets 4014 Silver, 18 in x 48 in 250 mil, 15 sheets per pack 1 pack per case Boxed 3M(TM) Damping Aluminum Foam Sheet 4014 Silver, open cell polyurethane foam with aluminum constraining layer on one side and a pressure sensitive acrylic adhesive on the opposite side, easy release liner 3M(TM) Damping Aluminum Foam Sheet 4014 are designed for damping resonant vibrations in thin sheet metal, resulting in attenuated resonant amplitudes and consequent noise reduction.