Micro valves are available as both screw top and crimp top vials. When used with a glass vial, only PTFE and glass are in contact with the contents. Operation is extremely simple, using the green and red buttons in tandem with a needle inserted through the septum to retrieve the sample. Micro push-bottom valves are highly dependable, leak-tight closures for vials and other laboratory containers. They provide an inert, high-pressure seal, and can be used repeatedly for unlimited syringe-needle access to sample.