Essential oil diffuser necklace on sliding knot adjustable cord. Charms each contain a lava stone bead. Dolphins and turtle- 6mm lava stone Owl and frog- 8mm lava stone Elephant- 10mm lava stone Add a drop of essential oil to the lava stone. Scents can last for several hours. Please note that charms cannot be opened while on chain. Chain: Adjustable length sliding knot nylon rattail cord chain. Can be adjusted by moving knots closer together or apart.