Swagelok fittings are easy to install and come in a wide variety of configurations. They form gas-tight seals that are resistant to vibration fatigue and capable of withstanding high-pressures, vibrations, and temperature changes. The patented advanced-geometry back ferrule design provides a leak-tight tube connection on all Swagelok stainless steel tube fittings of identical sizes. When installed, the front ferrule creates a seal against the fitting body and on the outside diameter of the tubing. Fitting Size: 1/4 inch Ferrule Inner Diameter: 1/4 inch Corresponding Back Ferrule: (09903120)