Pyramid Acoustic Foam
Pyramid foam, like our wedge foam, is a long-lasting, high-performance solution to your sound-deadening needs at an affordable price. Pyramid foam's unique design offers slightly different performance characteristics than the wedge foam, with its greater surface area. The four sides, rather than the two of the wedge, offer extra diffusion but slightly less absorption for different usage styles.
More information: http://www.thefoamfactory.com/acousticfoam/pyramidfoam.html