Vials are used basically to inject samples from an autosampler. Autosampler needle pierces through the cap during injection and withdraws the required aliquots of sample from the vials. Screw top glass vials are used on many autosamplers with a standard opening of 4.6 mm. Amber glass prevents the samples from exposure to UV light. The threads on the standard opening vials are 8-425. Includes a phenolic open top cap and a red PTFE/silicone septum suitable for use with most organic solvents (until pierced) and not recommended for use with chlorosilanes.