Spring Seal/ spring energized seal/ Variseal is a U-shaped Teflon high-performance seal with a special spring inside. By the appropriate spring force plus the system fluid pressure, the sealing lip (surface) is pushed out. Gently press down on the metal surface being sealed to create a very good seal. The actuation effect of the spring can overcome the slight eccentricity of the metal mating surface and the wear of the sealing lip, while maintaining the expected sealing performance.