Preassembled R.A.M.™ Smooth Screw Thread Closure with Ultra Low Bleed Septa for Mass Spec and Sensitive Analysis. 9mm R.A.M.™ Smooth Screw Thread Closure is lined using a LCMS high-purity septa. This septa is ideal for very sensitive applications such as Mass Spec or when multiple injections are required. Our Ultra Low Bleed Septa eliminates particulates with no interfering peeks.