Breza Aquatop AS-04DSK Increases surface agitation & water oxygenation Helps release carbon dioxide build up For use in all aquariums Installation: 1. Soak the air stone in water for approx. one hour before operating. 2. Position in tank. Bury the bottom 1/3 with gravel or stones. 3. Attach air pump with airline tubing and a check valve (sold separately). ATP AIRSTONE DISK 4IN