SilTite™ metal ferrules have been developed specifically for use with GC/MS systems and have distinct advantages over graphite and composite ferrules for use with GC/MS interfaces. The metal SilTite™ ferrule and nut are made from the same material and therefore have the same thermal expansion coefficient. As the oven heats up and cools down, the nuts and ferrules expand and contract at the same rate, eliminating annoying leaks and the need to retighten the ferrule after installation. SilTite™ nuts are reusable. Unlike graphite Vespel® ferrules that are nearly impossible to remove from the nuts after use, SilTite™ ferrules are easily removed from the specially designed nut while still attached to the capillary column. 15% Graphite / 85% Vespel® Ferrules are made of hard material that is mechanically robust. Forms strong grip with column but cannot be re-used with another capillary column. They must be retightened after initial temperature cycles. Temperature limit is 350° C. For use with GC-MS interfaces. 100% Graphite Ferrules are inherently softer allowing for a "form-fit" seal. They are easy to use. These reusable ferrules form a stable seal at temperatures up to 450° C. Porous to O2, these ferrules are not for GC- MS applications. All ferrules come in packs of 10, unless otherwise noted.