Hydroponic Air Injection unit for any DWC/system,Aeration Diffuser BubblerAir Injection unit for any DWC/system,Aeration Diffuser Bubbler This system is designed to give you more air and air where the average air stones dont go if you buy the right size AIU Air Injection Unit for your Pot, Bucket, or Tote, there will be no dead areas and will keep your oxygen levels the same all the way through your system.The AIU Produces much smaller bubbles than the average air stone and very easy to clean.Please NOTE when ordering diameter size includes the weights.8" DIAMETER / WITHOUT WEIGHTS on 9"/ DIAMETER WITH WEIGHTS ON 6" DIAMETER / WITHOUT WEIGHTS on 7"/ DIAMETER WITH WEIGHTS ON Connection to air inlet is 4mm All weights are made from A4 MARINE GRADE STAINLESS STEELwill not rust rot or alter your PH if you buy these units from me or any other seller always ask what metal the weights are made of some of the cheaper metals rust and rot and can kill your roots. if you dont see the size you want look at my other listings all units will be delivered with the metal weights unattached for you to put on yourself if i were to put them on and send them it would more than double the postage cost. If you dont see the size you want or have any questions please email. COPY AND PASTE ADDRESS BELOW TO SEE VIDEO OF UNIT WORKING https://www.youtube.com/watch?v=TykVx854tK8&t=6s AIR UNIT IN VIDEO IS A 9.5 DIA IN A 21LTR BUCKET a question i get asked most is do they come as a kit for customers to make up themselves like some others that sell them on ebay no they get sent out 99% made up you just have to put weights on 2min job why pay for something then have to make it yourself.