This 21 inch drop ruffled bed skirt is the Perfect solution to quilts and comforters that are not  wide enough to cover the entire mattress on both sides.  (Or, for example , if you have a bed that is also higher up off the ground. ) 
Just place the bed skirt underneath your comforter or duvet, yet on top of the "top sheet". (So it's between your comforter or duvet and your top sheet. It's invisible.) It covers the mattress, box springs, washes and dries nicely, and layers perfectly under your quilt or comforter!!