The 133 Series U-cup seal is one of System Seals’ most popular designs used in high clearance applications. The symmetrical design utilizes an O-ring loader to maximize lip force, and a backup ring to prevent extrusion. The symmetrical design ensures that the seal lip forces are equal for every cross section and diameter. Manufactured in a variety of materials and sizes from 6 mm up to 2100 mm in standard and custom diameters.