A small piece of non-toxic plastic that allows you to connect two or more air lines. The straight connector allows you to connect two pieces of short air line. The L connector is ideal for 90 degree corners. The Y and T connectors can split your air tubing to run a second air stone from the same pump. You can also combine two inlets to create a more powerful output for use with multi-outlet pumps. Works well on a standard 0.5cm diameter breathing circuit which fits most air pumps. air. Includes 10 T connectors, 10 straight connectors, 10 Y connectors and 10 elbow connectors.