It is meticulously designed to provide a secure and reliable seal for 5 mm NMR tubes, ensuring sample integrity during nuclear magnetic resonance spectroscopy. Constructed from high-quality silicone with a white exterior and a blue PTFE (polytetrafluoroethylene) lining, these caps offer exceptional chemical resistance and durability. With a hardness rating of 55° Shore A and a thickness of 0.9 mm, the slitted design facilitates the addition of substances into the closed tube for titration experiments without the need to open the tube, enhancing convenience and maintaining an airtight seal. Packaged in sets of 100, these septum caps are essential accessories for laboratories seeking consistent and dependable sample containment solutions.