Made from 100% recycled glass sintered to form rigid, lightweight, porous sound absorbers, Phonstop V has noise reduction coefficient to 0.9 to reduce reverberation and echo. Tiles can be adhered directly to walls and ceilings. For indoor and outdoor use, panels measure 24 x 24 x 2 in. and 24 x 48 x 2 in. One tile face has 3/8 in. chamfer beveled edges; reverse face has square edges.