High porosity Airstone Produces an even flow of fine pearlescent air bubbles. Minimal back pressure maximises the full capacity and liftetime of your air pump Manufactured to high quality specifications for longer life. Tetratec airstones are designed to be run with any aquarium air pump such as the TetratecAPS range and standard aquarium airline hose.For maximium aeration the airstone should be placed as deep as possible within the aquarium. Dimensions 27mm x 40mm long