These reusable iDOO Pod Cover are designed to help prevent algae growth by restricting some of the light to the root system. This is 3D printed in PLA which is a biodegradable food safe material. It is approximately 38 mm round with a ring in the middle to help give the plants extra support at the root May be hand washed with cool water & then air dried. This is a set of three spacer Check out all of our other iDOO supplies on our Etsy store. We have many things including replacement pods, jar growing systems & growing cages. These do not fit the AeroGarden they are for an IDOO growing system. If you have any questions about Aerogardens, Kratky or Hydroponics please join our support group https://www.facebook.com/groups/218267669995724/ Idoo Growing Pod Covers