Spectra Premium FN558 Fuel Tank Filler Neck Unit is designed to Original Equipment (OE) fit, form and function requirements Fit tested on vehicle application for which it was developed verifying first-hand that the design fits properly and can be easily installed Dual coated for enhanced corrosion protection Unit is leak tested after production to ensure product in free from fuel and/or evaporative leaks Tested with Original Equipment (OE) fuel cap to prevent EVAP and check engine light failure