30 sheets of acoustic foam for the use in studios and home theatres to improved the acoustics of the recording or listening environments. Effectively minimizes the reflection of sound, for mid to high frequencies. Great at reducing feedback and cymbal hiss often heard in practice jam rooms with drum kits. The conical pattern of the foam is scientifically proven to minimize the reflection of sound, eliminating much of physical cause of feedback when using microphones. The foam can be attached to a wall using a variety of fixers including staples, nails, screws, tacs, glue, velcro. It really depends on the wall. Specifications: Dimensions: 500mm x 500mm Density: 25kg/m3 Thickness: 50mm (from base to tip of cone) Area Coverage: 7.5m2 (7.5 Square Meters) Colour: Black Material: Expanded Polyurethane Foam