The SWT series is a sunsep™ hollow fiber covered with a resin net. This structure protects the sunsep™ hollow fiber membrane while allowing it to freely exchange moisture with the ambient environment. The humidity differential between the ambient air and the inside of the membrane drives the dehumidification or humidification of the sample gas at micro flow rates of 300 mL/min or less, without the use of a purge gas stream. The SWT series is used in breath analyzers, metabolism monitors, etc.