RK Racing Chain Series apply RK?s only technology of Ultra Thin Seal, U-Rings or UW-Rings, where the thickness of seal is less than 50% of the common seal, make it possible to design a Sealed Chain with the weight of...
RK XSO Series: Designed for Basic Motorcycle Models, Features RX-Ring that have ?X? shaped seals and improved metallurgy giving you 2 times longer wearlife than standard O-Ring chains."
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