EasyPro, Airmax,"GREAT LAKES" -"SWEETWATER", Pond Logic"REPLACEMENT AIR DIFFUSERS" by Bubblemac Industries, Inc. {The ORIGINAL manufacturers of the"Sweetwater" products line from 2000-2015}. SIMPLY UNSCREW THEIRS AND SCREW OURS IN!! That's how easy it is to replace the membrane diffuser sticks that came stock with your EasyPro, AirMax or Pond Logic Underlayment. If you are tired of replacing the low-quality import "air-stones?" that came with your system, now you can replace the diffusers ONE LAST TIME! Bubblemac Industries High-Quality 100% Glass-Bonded Silica Air Diffusers are The Most Efficient, Most Affordable and Require the Least Amount of Maintenance. Each Bubblemac Air Diffuser Measures 1.5" x 1.5" x 6" with a 1/2" MPT Fitting That Will Thread Directly Into The "GREAT LAKES", EasyPro, AirMax or PondLogic Manifold Underlayment. {Suggested CFM=1.0 or 28 lpm} Made In The USA With A Two-Year Warranty. All Bubblemac Aeration Products Boast A "NO QUESTIONS ASKED" Return Policy. If You Do Not Agree That Our Products Outperform The Competetions "membrane diffusers," Return Them For A Full Refund! -- BEWARE OF IMITATIONS: Bubblemac diffusers are the original 2000F glass-bonded silica air diffusers introduced by Bob Heideman, founder of Aquatic Eco-Systems in 1978. Specs: Maximum Pore Size 140 Microns, Nominal Partical Retention 50 Microns, Flexural Strength 2500 PSI, Bubble Size 1-3 MM, SERVICE LIFE UNLIMITED When Used In pH of 8.0 Or Less. These Air Diffusers Should Not Need To Be Cleaned For One Full Year. When Cleaning Is Necessary, Simply Bath In A Diluted Solution Of Muriatic Acid {mild swimming pool acid} Diffusers Replace Those On The Following Models: ANY GREAT LAKES UNDERLAYMENT, EASYPRO DM-2, DM-4 and DM-6. PONDLOGIC KOIAIR 1 and KOIAIR 2, AIRMAX #160135 {8000-16,000 gal}, OUTDOOR WATER SOLUTIONS #ARS0124 -4 way. -- Pictures Are As Follows: #1- The EasyPro Underlayment With Two High-Quality Bubblemac Air Diffusers Installed. #2- The EasyPro Manifold As It Comes Stock, #3 & #4- These Pictures Provide A Side-By-Side Comparison.