Bubblemac fine bubble air stone measures {1" x 1" x 1" } with 3/16" OD barb. Requires .15 CFM or 4.25 LPM to function as designed. Fine bubble aeration is an efficient technique of aeration in terms of oxygen transfer due to the large collective surface area of its bubbles and thus transfer more oxygen to the water per bubble. Additionally, smaller bubbles take more time to reach the surface so not only is the surface area maximized but so are the number of seconds each bubble spends in the water, allowing it more time to transfer oxygen to the water