Nalgene MF75 Series Polystyrene Lab Filter Unit, Nylon, Red Collar,, 0.2 Micron, 50mm Membrane Diameter, 250mL Capacity (Case of 12) Upper capacity: 250ml Receiver capacity: 250ml Material: polystyrene with a nylon membrane Membrane diameter: 50mm; pore size: 0.2m Red collar