6.8oz / 200ml of reed diffuser oil in a reusable refill bottle, these are the perfect size for refilling our Refillable Reed Diffuser vessels. Diffuser oil comes in a PET Plastic bottle. What is PET? Unlike other types of plastic, PET plastic is not single-use -- it is 100% recyclable, versatile, and made to be remade or refilled. When you are done with your refill bottle they can be returned and I can refill your bottle again and again!