These Revolutionary Media Reactors have a fluidizing cone bottom design to help keep the Biopellet media in suspension and evenly disperse the water upwards, without restricting the flow through the unit. These advanced reactor units also includes fastening screws on the lid for a sure tight seal and a mesh screen to keep the biopellets within the reactor without the risk of restricting flow or clogging like other media reactors on the market. These units come in 3 different sizes.