20mm Aluminum Seals, Ultra Low Bleed Septa, for Headspace & SPME Vials. $400.60. $375. 20mm BiMetal Seals, Magnetic, for Headspace & SPME Vials. $40 and up. 20mm Crimp Headspace Vials, Beveled Bottom. $253.28. $241 and up. 20mm Crimp Headspace Vials, Flat Bottom.