Bonded Acoustical Cotton High-Density Composite Panels Echo Eliminator Composite, made from bonded acoustical cotton (B.A.C.) with a foil FRK facing, is a cost-effective dual-purpose acoustical absorber and noise barrier. Made from recycled cotton, this high-performance acoustical panel is ideal for any noise control application. Echo Eliminator Composite panels are easily installed with adhesive, fiberglass free, and may be eligible for LEED™ credits.