Perifusion Chamber FilterA fiberglass filter sheet is included with every perifusion system. A hole puncher can be used to make round cut outs of the filter sheet to place inside the perifusion chamber during its set up. The purpose of this filter is to retain the chamber contents while allowing the flow of the perfusate. Each Biorep Perifusion Chamber uses one disposable, single use filter. Nominal Porosity: 4um Sold in packs of 10 (63mm squares)