Screw-Thread Vials found in: Autosampler Vials, 12x32mm with 9mm Screw Thread, 9-425 Screw Thread Closures, for use with R.A.M. Vials, Screw.. magnet Round bottom vials distribute the internal pressure created at high temperatures across the glass surface and are more easily handled by robotic arms that lift the vial from the tray Uniform wall thickness for even heat distribution Headspace