Quality Headspace Vials and Closures from J.G. Finneran The vial’s wide opening allow for samples to be easily added, and all 20mL headspace vials are available with a marking spot. Our rounded bottom vials, designed for high pressure strength during the heating process, or flat bottom vials, are available in 6mL, 0mL, 20mL, 27mL capacities, in 20mm crimp or 8mm screw thread.