20mm AL Crimp Cap & Silicone/PTFE Septa, Kit, flat bottom, 100/pk. Package of 10mL clear headspace flat bottom vials with 20mm aluminum crimp caps (silver in color) and Silicone/PTFE Septa. Cap: 20mm silver aluminum crimp Headspace Vials - Worldwide Glass Resources, Inc. - Vials. Manufactured from low extractable Type I borosilicate glass.