This 115mL low-profile polystyrene housing unit with a polyethersulfone (PES) filter unit that is ideal for small-volume benchtop filtration. Low-profile with wide stable base design. Pore size and membrane type are printed in easy-to-see blue on the side of each unit. Polystyrene housing. Polyethersulfone (PES) filter. Membrane diameter: 50mm. Pore size: 0.45µm. Capacity: 115mL. Nalgene #: 124-0045.