The 12" CornerFill is a 12" x 12" x 24" section of flat-cut Studiofoam acoustic absorber that is beneficial in two ways.
Aesthetically, it provides a smooth, clean edge against which to butt other acoustic wall treatments and acoustic foam bass traps for a more professional appearance. Size wise, it is very suitable for use with Venus Bass Traps.
Acoustically, it smoothes out the excess low frequency energy that congregates in room corners.