NAFTOSEAL® MC-780 Class B is a two-component, manganese-dioxide cured polysulfide polymer system with low density providing excellent fuel tank and fuselage seals. NAFTOSEALl® MC-780 Class B maintains its flexibility and bond strength on most metal substrates like aluminium, stainless steel, steel, titanium, composite and many coatings under extremes of temperature, weathering and stress. It has outstanding resistance to aviation gasoline and jet fuel, as well as resistance to the chemicals and petroleum products used in the aircraft industry. Additionally, it was developed for a service temperature between -55 °C (-67 °F) to +130 °C (+ 266 °F) and withstand a shortterm temperature of +182 °C (+360 °F).