Aluminum Crimp Caps For GC - Autosampler Vial, Hplc Vial. 20mm Open Top Aluminum Crimp Cap (10mm hole) with 20mm White PTFE/White Silicone Septa 3mm Thick. 100pcs/pk. * Product Introduction Constructed of aluminum, these crimp vials are ideal for use with your crimp neck vials.Aluminum crimps tightly around the neck for a tight seal.