Autosampler Vials, Caps, and Closures - Fisher Scientific. Autosampler Vials, Caps, and Closures glass vial caps supplier Scientific™ 20 mm Headspace Vials, Septum, and Caps Headspace vials are available in clear or aer glass with a round or flat base, a crimp seal with a beveled or square edge finish, or with a screw-thread finish.