This stretcher is made of plastic that falls apart in random-sized small bits as you stretch the shoe.  One of the bits was quite sharp but most of them are like cookie crumbs. At first I thought I had sand in my shoe until I looked at the crumbs closely and then tried it on another clean shoe.  The device continued to work, but I have since bought a set of solid wood stretchers, worth it, since these were a waste of money.