Style ST-XL-PM wipers are molded from 55D polyester and are direct replacements for Style "ST", "ST-XL" or "D" wipers. The polyester based material provides a tough abrasion resistant wiper for heavy contaminant environments. The outside diameter of the ring has a crush lip providing extra interference in the groove. A bead on the shoulder stops contaminates from entering through the groove. The inside diameter is ribbed to prevent pressure traps between the wiper and rod seal.