Gas Sampling Bags’ patented 2-in-1 fitting combines a shut-off valve and a fluoropolymer-lined septum—allowing you to fill the bag and remove the sample for analysis with one fitting. The polypropylene stem is used to connect 1/8" I.D. tubing for filling and emptying the bag. Use the septum to remove the sample using a needle and syringe. Always ensure the gas sample bag, fitting and tubing materials are appropriate for the compounds being sampled.