All natural, responsibly harvested rattan. Our reeds are 3mm in diameter, for maximum flow or “wicking” of reed diffuser oil. The slightly wider reed also helps get thicker fragrances “airborne”. Reeds come in a bundle of 8. We find that 3-5 works just fine, but many people add more (8,10,12+). Know that the more reeds you use, the more fragrance that is released, and the quicker the liquid is used up.