Aquarium LONG-LASTING Air Stone 2" Fish Tank Aerator Diffuser Hydroponics - 6 pcs Last at least 3 times longer than regular air stone Great for freshwater, saltwater/reef aquariums and hydroponic use Increase oxygen levels, "blow off" CO2 and raise pH Fits standard air line tubing aquarium and CO2 tubing with inner diameter of 3/16" DIMENSIONS: 3/4 " D x 2" H INCLUDES: 6 pieces of air stones