20mm Open Top Aluminum Crimp Cap (10mm hole) with 20mm Natural PTFE/White Silicone Septa 3mm Thick. C0000197. 100pcs/pk. 20mm Open Top Aluminum Crimp Cap (10mm hole) with 20mm Natural PTFE/Blue Silicone Septa 3mm Thick. C0000198. 100pcs/pk. 20mm Open Top Aluminum Crimp Cap (10mm hole) with 20mm White PTFE/White Silicone Septa 3mm Thick