Micro-Bubble Diffuser {Twin} for Hydroponic/Aquaponic Systems; manufactured by Bubblemac Industries, Inc. Aeration Products - 100% Glass-Bonded Silica Fine Pore Air Diffusers- Self-Weighted Design This Bubblemac Micro-Bubble Diffuser {twin}produces uniform "Ultra Fine Bubbles". Smaller Bubbles provide more surface area, creating a more Efficient Oxygen Transfer Rate. Designed specifically for 50 gallon Hydroponic Systems. High-Quality unit comes complete with two Bubblemac Ultra-Fine Pore 100% Glass-Bonded Silica Air Diffusers. {diffusers measure 3/4" x 3/4" x 3 1/2" with 1/4" poly NPT fittings} Compatable with most low cost air pumps and compressors, the unit now comes complete with three standard air hose connection barbed poly fittings - 3/16", 1/4", and 3/8" {Suggested CFM = 0.6 or 16-18 lpm} -- Bubblemac Aeration Products Provide An Effective, Yet "UNIQUE" Alternative To The Import Blue Air Stones....... These diffusers WILL NOT fall apart or fail; they last a long time! This Bubblemac Hydroponic Air Lift System is UNLIKE the one-piece import systems which are manufactured for pennies and sold to the consumer for big $$. Made in the U.S.A. This system is guaranteed to "OUT-PERFORM" the others hands-down! Simply Put, this Hydroponic Aeration System is the Highest Quality, Lowest Maintenance and Most Durable Choice for Aeration. Perfect for any tank where you suspect an issue with dissolved oxygen. EFFECTIVE and ECONOMICAL...easy to clean and maintain. - SPECS: 100% Glass-Bonded Silica, Maximum Pore Size 80 Microns, Nominal Partical Retention 25 Microns, Flexural Strength 3500 PSI, UNLIMITED LIFETIME When Used in pH of 8.0 or Less!