Aquatix Pro Large Air Stone Cylinder Premium Quality, Air Stones are Best for Aquariums, Fish Tanks, Ponds or Hydroponic Systems, Air Stone Diffuser Produces Fine Bubbles for Oxygen Replacement (1) GET RESULTS: Large Hydroponic Air Stone Adds Oxygen to YOUR growing system, will aerate and circulate nutrition, keep roots healthy and provide exceptional growth. PREMIUM QUALITY: Large in size (4" x 2"), Strong, durable and long lasting air stones helping you maintain any type of system. COMPATIBLE: Ideal Air buuble Stone for hydroponic growth, fish tanks, fish ponds, aquariums and other systems. OXYGEN REPLACEMENT: Round Air Stone produces fine bubbles in producing oxygen replacement for fish tanks & ponds. OUR GUARANTEE: 100% money back guarantee whatever the reason - no questions asked!