GSC Power Division Viton Evo 4B11T Valve Stem Seals use genuine DuPont Viton® fluoroelastomer material GSC Power Division Stem Seals Mitsubishi . Viton® was specifically developed for the extreme conditions seen in today’s high horsepower, sport compact engines. Held to a higher standard, GSC Power-Division Viton® valve seals provide improved resistance to high temperatures, fuel, and chemical contaminants as well as extended wear as seen in high rpm or high mileage engines. GSC Power-Division doesn’t believe in cutting corners, that’s why the Viton® valve seal kits are used on both the intake and exhaust valve seals. All of this performance for a fraction of OEM dealership parts, GSC’s Viton® valve seals are perfect for all situations.