Installs in one of our 20x20 wine plate filter units to allow you to change pore size of your pads halfway through the filter. For example, turn a 20 plate filter into two 10 plate filters for sequential rough (7 micron) then polish (3 micron) filtrations in one unit. Fits all of our 20cm x 20cm plate filters. Includes stainless plate and 2 black noryl end plates that install on each side of the stainless plate.