4 Inch (100mm) Heavy Duty Airstone Disc for Koi Fish Ponds or Large Aquariums 4" Round Heavy Duty Disc Pond Aquarium Airstone Aeration is a important part of pond and aquarium care, maintaining oxygen levels and helping fish stock levels. Air stones allow oxygen to get to the roots of the plants to keep a healthy eco system improving water quality and circulation. Aeration stones are also called air stones, discs, bubblers or diffusers and come in many shapes, sizes, colors and coarseness levels. They do not clog and give a better distribution of air with finer bubbles than other types of aeration systems. Airstones are very durable and extremely easy to clean. Safe for all types of lakes, ponds, fresh water aquariums, salt water or marine fish tanks. ? 4 Inch (100mm) Diameter Round ? Dual Standard Nipple 3/16th/ 5/16th ? Fine Diffuse of Bubbles ? Heavy Design ? Suitable For Ponds and Large Aquariums We sell many aquatic products online, check out our store! Terms and Conditions. We use all approved forms for accepting payments. Sales Tax will be added to all shipments based on regulations. We always try to combine purchases, please contact us directly for a personal service. You will be notified on the day that your goods have been dispatched via e-mail with tracking which is used on all purchases. Please note that if there are any problems, contact us first via e-mail giving full details of any problem along with your user ID. We use USPS and UPS as our chosen carriers shipments to Hawaii, Alaska Puerto Rico may incur surcharges, contact will be made to advise before shipment at which point the order can be cancelled if desired. Orders placed on Saturday/Sunday Public Holidays will be processed next working day. We pride ourselves on excellent feedback, if any part of the buying experience is not to your satisfaction, please contact us to rectify before leaving feedback. By committing to buy you are agreeing to the Terms Conditions stated above.