I really think there are fine nano particles of something sharp either on top or embedded in these things. Haven?t had issues with it coming off like others have said in their reviews. One thing sets these beads apart from their more famous (and expensive) counterpart: Quality Control (or lack thereof). Marshall is a good British brand so Im happy to endorse this as a very good Bluetooth speaker. Not having the abilty to change the wake word on the Bose 300 was the final straw in returning it. The 3 pins on the plug are so weak and the plug base is so hard to rotate that pins will break if you use a screwdriver to rotate the plug. ??????????????????????????????? I would definitely recommend this product to you ladies out there! That explains why these shoes arent nearly as great as the reviews. The silliest reality show I have ever seen.