Features: 1. Made of natural wooden material, which is soft, lightweight and durable. 2. Wooden air stones create very fine and even bubbles, can greatly dissolve oxygen and increase oxygen in the water. 3. Rich color and smooth texture design, with good elasticity, comfortable to use. 4. Suitable for marine aquariums and fresh water. You need to use this product with the air pump (Not Included). 5. It is suggest to replace the wooden air diffuser one time every 2~3 months. Specification: Condition:100% Brand New Material: Wooden Color: As Pictures Shown Type: S, L(Optional) Size: Small Length: approx.4.2cm/1.7in Large Length: approx.6.2cm/2.4in Package list: 2 * Wooden Air Diffuser Note: With the right choice of oxygen pump (below 5W), the wooden air bubble can produce a large number of uniform and fine foam, thus separating impurities in the sea water. (please do not use the air pump with too much air volume, which may cause the air wood to become loose, in this case, you need to roll a layer of water adhesive cloth and put it back in.) Please note that the head color of this product will be sent randomly, please make sure you don't mind before ordering.