Specially designed, opened cell, flame retardant foam in a convoluted "egg crate" pattern. Helps to reduce muddy bass and cleans up the midrange by absorbing internal standing waves. Staple or glue to the top, bottom, sides and back of your speaker cabinet. You will be amazed at what acoustic foam can do for your sound system. Also ideal for small recording rooms and studios. Flame retardant in accordance with UL 94 HF-1 flammability testing. Sold individually in 24" x 18" pieces. Charcoal gray color.