Rubber Gaskets And Seals Includes O-rings, stem seals, rotary seals, and mechanical seals. Unlike gaskets, which are typically used for static applications, seals are found in more active environments for motors, engines, pumps, and rotating shafts. Seals tend to be flat and rounded, with a slanted rubber inner ring around the metal outer ring. The inclined Angle of the sealing inner layer helps prevent leakage in dynamic applications.