Mouse over image to zoom Have one to sell? Sell now 6 PCS 1-3/16" Blue Air Stone Aquarium Fish Tank Aerator Diffuser Hydroponics 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 4 mm DIMENSIONS: 1-3/16" Dia. INCLUDES: 6 pieces of air stones Standard Shipping (USPS First Class Package)