Soft to penetrate, high purity Silicone/PTFE closure for sensitive analysis. Can be used at very high temperatures. The bridges of the cap's scorelines break open at an internal vial pressure exceeding 3 bars (± 0.5 bars), thus releasing overpressure in a crontrolled way. Functionality of the cap is not depending on the design of the vial's crimp neck (beveled top, flat crimp neck).