Wheaton screw caps, white, 22-400 with ptfe /silicone liner (22-400 cap, open, pp, white, ptfe/ silicone liner .060) 22-400 open top cap, pp, white, ptfe /silicone, liner .060. Use these caps with or other manufacturer’s numbered glass bottles or vials open top caps provide access with a syringe these polypropylene autoclavable open top caps have a bonded ptfe faced silicone liner making them ideal for storage and retrieval of volatile solvents, sensitive compounds and corrosive chemicals the liners consist of 0.055″ (1.4 mm) of silicone and 0.005″ (0.14 mm) of ptfe. Warning: this product can expose you to chemicals including tetrafluoroethylene, which are known to the state of california to cause cancer. Prop 65 warning