Heavy wall glass storage bottles with #15 Ace-Thred are intended only for storage of low-boiling liquids at room temps or at not less than -20°deg;C. Designed to resist internal pressures up to 100 psi, as low as -20°deg;C. The low pressure rating based primarily on the rating for PTFE T.F.E. Safety coated to the neck to help prevent shattering and reduce spills. Closures are inert PTFE plugs with FETFE o-rings that will not freeze. 2 closure styles: with o-ring positioned at the front of the thread or with o-ring at the back of the thread.