This funnel only product is made up of a polystyrene funnel with a 0.22µM PES heat sealed membrane. The funnel is molded from USP Class VI, FDA Grade Polystyrene resin and are sold presterilized. The funnel is designed to be used with the pedestal and cradle ring hardware which create the seal needed for applying the vacuum. Membrane: Sterilizing Grade PES. Volume: 500mL. Pore Size: 22µM. CapitolBrand®.