5.Butyl/PTFE, Pharma-Fix-Liner (Butyl/PTFE), Silicone/PTFE are all Available . 6.Rounded or flat bottom profiles are available for accurate instrument compatibility. 7.6ml crimp top headspace vial with matched 20mm Aluminum & Magnetic Aluminum cap, 20mm PTFE/rubber septa Features . 1).Crimp caps provide a consistently secure seal