David...air stone is a piece of porous material that the air line is fed into... it is an open cell item... so the big bubbles that you'd get with just an air line .. are broken up into thousands of little bubbles... the mass of little bubbles go into suspension in the water easier.. providing an oxygen rich water.. or healthy fish...and brush along the stem you are rooting.. stiring the cutting to reach out and start making roots faster..http://www.amazon.com/s/?ie=UTF8&keywords=air+stone&tag=mh0b-20&index=aps&hvadid=3527181225&hvqmt=p&hvbmt=bp&hvdev=c&ref=pd_sl_6bec94asxd_p
