CornerFills are long, thin rods of flat-cut Studiofoam that are beneficial in two ways. Acoustically, they smooth out excess low-frequency energy that congregates in room corners. Aesthetically, they give you smooth, clean edges to butt your Studiofoam, SonoMatt and Venus Bass Traps up to for a more professional appearance. These are highly recommended to give your sound the treatment it deserves.