Key Features High Oxygen Air Cylinder Made of silica for the finest air bubbles For use within Aquariums Can also be used in ponds with the relevant airline. 130mm x 30mm High-oxygen air cylinders with protruding end caps to keep them clear of pond liners. Made of silica for finest air bubbles and long life. The 130 x 30mm air cylinder is designed for use within aquariums, but can be used in pond set ups with the relevent airline tubing and air pump set up.