FK Series Medium-Pressure Tube Fittings from Swagelok meet requirements for H70 (700 bar) hydrogen fuel service in hydrogen-powered vehicles. Swagelok fittings enable fabricators to create repeatable, leak-tight connections that are not prone to failure from vibration, corrosion or other factors. FK Series fittings feature two ferrules which provide a hinging colleting action to securely grip the tube. The hardened ferrules provide direct and axial support to mitigate the effects of vibration and maintain a leak-tight tube grip.