Petco Air Control & Check Valve Combo for Fresh & Saltwater Aquariums controls the air flow of air-driven aquarium devices such as action ornaments, bubble bars, and other aquatic devices powered by air pumps. The individual knobs allow for separate air flow adjustment for each device. The built-in check valve protects equipment in the event of a siphon. Durable, clear plastic valve can hang discreetly on most fresh or marine aquariums. Airline tubing snaps easily into the individual grooves to prevent tangles.