Soak in water and these beads grow 300 times their size!
These small beads can absorb up to 300 times their volume in water and grow many times their original size while maintaining their spherical shape. Soaked in water, they will expand up to 40mm (1.5") over a few hours. Plus, since they are almost entirely water when fully absorbed, they have the same refraction index as water and become invisible. Try adding food coloring to make them stand out. (Also, try distilled water for even more growth.)
The beads are made of super-absorbent polymer (SAP), a hydrogel that exploits the strength of hydrogen bonding of water molecules, and the same absorbent material used in diapers.
Hydrogen bonding is the force that causes water molecules to cling to each other. It is responsible for the formation of water drops and how some insects can stand on the surface of water.
These beads can also be dehydrated and reused and are biodegradable. So if they need to be disposed of, they are safe to throw in the trash.
Each bottle of beads has an accompanying information card.