China 20mm Crimp-top Magnetic Aluminum Caps with Septa ND20 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. 2).Beveled top for maximum secure seal. 3).Choice of a pressure safety release cap at 45 psi. 4).10/20mL Clear /Amber