Eastman's Steel-Flex. 3/4" FIP x 3/4" FIP x 18" Water Heater Connector is the standard in water heater supply lines. Its quality is determined by what you can't see. The supply line features a non-toxic pvc core, a multi-filament braided nylon reinforcement, a clear vinyl outer shell, and a grade 304 stainless steel braided exterior that is designed to prevent kinking and crimping. This flexible supply line resists corrosion and is easy to install.