How cute are these glass refillable diffusers for your car in your favorite Rich Bish Scents! To use you will unscrew the top, remove bung (cap keeping oil inside), replace the top which has wood inside, gently tip the diffuser letting the fragrance oil saturate the wood, you are now ready to hang your diffuser in your car! Holds 7ml of fragrance. String length 40cm. Car Diffusers come with 15ml refill glass bottles with a dropper.