Septa, 20mm, Headspace, Molded Butyl Rubber, Grey, completely laminated with transparent PTFE. For use in 20mm Crimp Caps, sold separately. MicroSolv Brand. Additional Info: Shaped, Butyl Rubber with Durometer of 50 Shore A, (hardness) and 3.0mm thick. Completely laminated with PTFE on both sides of the Septa. Temperature resistant from -40⁰ to 120⁰C. Use in Aluminum or Steel Crimp Caps for Headspace autosamplers.