520EXW is RK's premium quality 520 XW-Ring chain. XW-Ring chains are the best high-speed, extreme heat performance chains available today. So, If you've modified your ride into an extreme high-speed machine, you need the strength and performance of 520EXW. With a maximum tensile strength rated at 8500 foot pounds and suitable up to 750cc ATV/Quads and Off-Road bikes, 520EXW can handle anything you dish out! The "XW-ring" is made of an advanced Nitrile Butadiene composite and features three contact lips and two convex outer stabilizers. This means three lubrication pools to protect against high speed abrasion, extreme heat build up, torsional flex and loss of lubricant. Nitrile Butadiene composite is oil and contaminant resistant, and the "XW" seal design is compression and distortion resistant to provide the ultimate in efficiency and performance with absolutely no o-ring drag. The "XW-ring" provides the user with a 50% longer wear life than basic o-ring chains. Pin Length in mm: 20.8mm. Maximum Wear Life Index: 1000. Maximum Tensile in lbs/Ft: 8500lbs/ft. Masterlink Type: Clip. Weight in Lbs per 100 Links: 3.36lbs. Max cc: 400cc Street / 750cc Off-Road. 19.2 Links per foot. 15.875mm Pin to Pin center. Your original purchase of RK sealed-ring chain is warranted to be free of defects in material and workmanship for 20,000 miles of street riding or one-year of off-road use. There is absolutely no warranty of any kind for an RK Chain used in ANY racing competition.