RK Chain 520XRE-122L XW-RING NATURALRK's XRE series chains are the successor to XSO chains. Compared to XSO, XRE series chains feature a 20% longer wearlife. XRE chains include XW sealing rings which provide two lubrication pools which help protect against high speed abrasion and prevent dirt and debris from penetrating the inner rollers bushings of the chain. XRE series chains are available in 520, 525 & 530 pitch. XRE's features create a perfect balance between high tensile strength,