clear 20ml headspace vials with screw caps price 20ml clear headspace vials price for GC/MS Sigma-Aijiren HPLC Headspace vial, screw top, rounded bottom (vial only) volume 20 mL, clear glass vial, thread for 18, O.D. × H 22.5 mm × 75.5 mm, pkg of 100 ea pricing SU860098