Wheaton screw caps, white, 24-400 with ptfe /silicone liner (24-400 cap, pp white, .005 ptfe/.120 l) 24-400 cap, pp white, .005 ptfe /.120 silicone l. Open top polypropylene glass-filled cap provides greater heat resistance than other pp caps ptfe / silicone septa bonded to cap ideal for epa samples. Warning: this product can expose you to chemicals including tetrafluoroethylene, which are known to the state of california to cause cancer. Prop 65 warning