Auralex CornerFills are sections of flat-cut Studiofoam corner acoustic absorbers that are beneficial in two ways. Aesthetically, they give you smooth, clean edges against which to butt your acoustic wall treatments and acoustic foam bass traps for a more professional appearance. Acoustically, they smooth out the excess low-frequency energy that congregates in room corners. They're great for gyms and larger rooms. This pack includes nine pieces (18 lineal feet).