20ml Crimp Headspace Vials - chemhplc.com 20ml Crimp Headspace Vials gc vial 23mm outer diameter crimping ultra low bleed ptfe septa beveled edge La-Pha-Pack_Catalogue_EN_6.pdf 3.5.10 HPLC and GC Certified Vial KITs (Short Thread Vials and Short Thread Seals ND9) The closure contains a very soft ultra low bleed silicone septum.