Drying beads are a commercial product sold by Rhino Research.

Using drying beads is an economic and more efficient way of drying and storing seeds and other dried products. Drying beads are a zeolite dessicant that absorb and hold up to 20 - 25 percent of their initial weight in water. When enclosed in a container, the beads remove water from the air to maintain a low humidity environment without the need for heating. Drying Beads can be used to store with seeds, fruits, herbs, or other materials and can be regenerated by heating above 200°C for 3-4 hours to release the absorbed water.

More information from Rhino Research can be found on the official drying beads website.