certified volatile organic analysis vials PTFE silicone Available in three sizes with the standard 0.125in thick, I-Chem blue, PTFE/Silicone septa in an open top 24-414 Polypropylene cap. The I-Chem molded-in septa retainer ring holds the septa securely in place without bonding to the cap, so septa can be removed and replaced as needed. 40mL