Aquarium Bubble Stones/Air Stones/Air Diffusers; model# 3P1010; by Bubblemac Industries, Inc. 100% Glass-Bonded Medium Pore Silica Air Difffusers. {THREE PACK} Self-Weighted Design This Bubblemac Aeration Products Aquarium Air Stone will Outperform The Blue Import Stones "Hands-Down" EVERYTIME!! -- Are you tired of purchasing yet another package of the blue import stones only to discover some are broken right out of the package? Don't Waste Another Dollar On The Inexpensive, Ineffective Blue Stones! -- - Made in the USA The Diffuser Measures 1" x 1" x 1" and has a 3/16" Standard Air-Line Connection Barb. Compatable With Low-Cost Pumps and Compressors; This Air Stone Will Make Your Fish And Plants Happy! **Remember: Aeration Helps Increase Beneficial Bacteria!** Healthy Eco-Systems Have The Proper Balance Of Oxygen and Nutrients To Sustain Plants, Fish and Other Living Organisms. Long Considered "The Standard Of The Industry" 100% Glass-Bonded Silica Air Diffusers Have Been Used In Fish Hatcheries, College Labs And Lakes Worldwide For 30+ Years. -- "Made Locally / Used Globally" -- SPECS: Maximun 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 8.0 or Less. This air diffuser produces a uniform Medium Bubble.