Wheaton headspace vials, 10ml or 0.34oz clear, 20mm finish, type i borosilicate glass. Wheaton headspace vials feature rounded shoulders and bottoms, allowing for even heating and safer operation at higher pressures. The newly designed top provides a tighter seal with your septa. Vials are manufactured from type i borosilicate glass. (hspace conv pk, 10ml vial, ptfe/ silicone seal)headspace convenience pack, 10ml vials, ptfe /silicone, seal. 10 ml vials w/pressure release ptfe faced silicone seals. Vials, autosampler, headspace, glass, 6ml, 22mm dia. X 38mm h, accepts 20mm aluminum seals. Each convenience pack includes 100 vials and 100 aluminum seals. Warning: this product can expose you to chemicals including tetrafluoroethylene, which are known to the state of california to cause cancer. Prop 65 warning