Your Source For Millipore Membrane Filter & Sterile Membrane Filter MeticLab membranes can be manufactured from a number of materials, but most materials used to treat water are polymeric in nature. We offer a wide selection of pore size options for you to choose from, not only common sizes of 0.22μm & 0.45μm, but also custom sizes ranging from 0.1μm to 5μm.