SupelInert multi-layer foil gas sampling bags with Thermogreen LB-2 septa are ideal for sampling low molecular weight compounds such as carbon monoxide (CO), carbon dioxide (CO2) and permanent gases. They are also suitable for sampling sulfur compounds such as hydrogen sulfide (H2S), carbon disulfide (CS2) and mercaptans.. Multi-layer foil composed of two outer layers of aluminum film providing a great barrier to gases permeating through walls of the bag. Proven low-bleed Thermogreen LB-2 septa installed in the valve fitting. Chemically inert with moisture and light protection. Not recommended for low ppm VOCs due to background levels (we recommend the SupelInert PVDF Tedlar alternative film for VOCs). Two valve choices available: Screw Cap Valve (SCV) and Push/Pull Lock Valve (PLV). Sigma-Aldrich 30237-U Supel-Inert Multi-Layer Foil, 1 L Maximum Volume, 7" Width, 9" Length, Pack of 10. Country of Origin : United States. Part Number : 1198W64EA. Pack of : 10.