The Flex-Bands are what make the Vertical Spice Drawer Units unique (and patented) and provide the great and easy access to spices.
The bands are 2 mm in diameter with black polyester over a rubber core, crimped into a loop. Very similar to mini bungie cords or elastic hair bands (pony tail bands). We found our prototype material at a Craft Store (readily available) and now buy the material in bulk and make our own loops. We stock bands as "Accessories" for future replacements.
We have bands on the prototype units in our kitchen that are 7 years old and still performing. Yes, they will wear out, but they are an inexpensive replacement that makes our product design like no other.