The 12 included in this kit are 2 by 2, and their soundproofing material effectively kills standing waves and flutter echoes and, when used in conjunction with Auralex LENRD or Venus Bass Traps or our Sunburst Broadband Absorbers all sold separtely, can effectively tame the full ...The 12 included in this kit are 2 by 2, and their soundproofing material effectively kills standing waves and flutter echoes and, when used in conjunction with Auralex LENRD or Venus Bass Traps or our Sunburst Broadband Absorbers all sold separtely, can effectively tame the full-frequency bandwidth in virtually any acoustic environment. The Studiofoam Pyramids offer a bit of extra sound diffusion and slightly less sound absorption than 2 Studiofoam Wedges, so they yield a less dry-sounding space with a bit more air.For installation, Studiofoam Pyramids require Auralex Foamtak spray adhesive sold separately, see 422605, which allows you to remove the foam later.