18mm Magnetic Screw Cap, Silver with Blue PTFE/White Silicone Septa, 1.5mm, (Shore A 55)

Alternative to:
La-Pha-Pack: 18 03 1414, Chromacol: 18-MSC-ST3 (alt.), Agilent: 5188-2759, Fisher: 11853912, VWR: 548-0245