Mar 29, 2022 · 20mm Aluminum Cap. The 20mm Crimp Cap is often used with Headspace Vial. It is tightly sealed and suitable for long-term storage of samples. The cap with center hole can be cut by septa, which is convenient for automatic sampling needle sampling. Rated 4.6 /5 based on 511 customer reviews. 20mm crimp closures aluminum closures crimp top closures.