Package Includes：25feet black tubing,4pcs air stones,4pcs check valves,4pcs black T connectors,12pcs black suction cups | Airline tubing: standard 3/16" diameter common to most airline accessories | Air stones: durable and can produce fine bubbles continuously to diffuse oxygen efficiently in your fish tank | Check valves: place these air pump check valves in your airline tubing between your air pump and aquarium water to prevent water returning down the air line | Suction cups and T connectors: fit 3/16 inch ID standard airline tubing