AkzoNobel 466-21 (21 Series) was a chemically cured two-component, flat topcoat designed to provide maximum protection from various chemicals, hydraulic fluids, aviation fuels, phosphate ester (Skydrol) fluids and corrosion causing media. This product is no longer manufactured, and AkzoNobel recommend the 466-23 (23 Series) topcoat as an alternative.