U.S. Patent #9,880,582
Care Instructions: Your Abacus Beads are designed to slide easily, yet stay in place when jiggled. This “grip’ is accomplished by special fingers molded into the Beads. To assure long life of the Bead Grip Fingers, avoid putting Mac’s Abacus in a Toy Box, where other items may press against the Beads. Also avoid placing objects on top of the Beads for any length of time. These types of actions could bend one of the Fingers, which may cause it to loosen its grip. Once the grip of a Bead is lost, it cannot be restored.
Always store Mac’s Abacus by laying it on a flat surface or by holding it upright in a stand (The Handle is useful for this).
Your Abacus Beads should maintain a useful grip for well over 200,000 moves under normal care.