Simple design, elastic draw cord and spandex fabric.  But it works perfectly.  Using it on a Yamaha full size keyboard.  It is not necessary to go over the top of the music stand if you don't want to; you can just cover the keyboard itself, and it still works/ looks great.  You could make your own copycat design for cheap, but would probably need a special (serger) sewing machine, several hours time, + source the supplies.  This is way easier and worth every penny.  Great fit on 88 key Yamaha.  Easy to take off, but a bit trickier to put it on, especially for kids (think fitted bed sheet sproingage).