ProMinent Fluid Controls 481003 3.68 X 1.78 Viton O-Ring for use with ProMinent pool and spa systems. Viton O-Rings are constructed from a strong fluoropolymer elastomer and synthetic rubber compound, making them ideal for even the most challenging applications. Able to withstand harsh chemicals, extreme weather, and UV exposure, these O-Rings are a top choice for many specialist and professionals.