Devices contain a PTFE membrane that provides highly efficient filtration in a very small area. Capsules with 1.0 µm pore size are supplied with a solvent-resistant polypropylene prefilter for extended life and are intended for use with highly contaminated solutions. The 0.05 and 0.1 µm filter devices are designed for "ultra-clean" applications. Typically used in biotechnology applications such as sterile vents and exhausts for growth environments and in-line sterilization, in the laboratory for clean or sterile gasses, solvents, reagents and drying gasses and in pharmaceutical research as vents and in-line filters.