Aquarium Air Stones/Air Diffusers/Bubble Stones {6 Pack}, Model# 1112-6; Manufactured by Bubblemac Industries, Inc Aeration Products. **Made Locally, Used Globally!**

Seem to really "Crank out the bubbles", but, then you would expect them to at $5.00 each, OUCH!'I'll be running 4 per tank in under gravel filter up tubes.....these stones are the large ones but they'll fit. Not sure about the optimum PSI/ CFM, etc. type requirements....given the bubble production it seems some fairly serious air production will be needed to run multiple stones.' I'm hoping they'll last at least couple of years as advertised 'UPDATE:Still "going strong" Dec. 2017. When inserting into the plastic tubes it was necessary to slightly grind each of the four corners to make slightly smaller. This worked perfectly, was very easy, and didn't hurt the stones at all.Great stones.....recommended 🙄

Second purchase and I know where to get more. Great product!