20 mm Magnetic Bi-Metal Cap/Septa w/3.0 mm 8 mm thickness 100 N6356565 PTFE/Blue Liner 20 mm Bi-Metal Cap/Septa w/3.0 mm Silicone 8 mm thickness 100 N6356566 PTFE Transparent Blue Liner Specialty Headspace Caps and Septa Description Pkg Part No. 20 mm Extreme Low Bleed 20 mm PTFE/Natural Crimp Septa Skived 1000 N9302976