The Next Level. Guaranteed. Mika Metals Factory Series Chains use exclusive next level bushings that slow elongation of the chain and increase chain life. They have the lowest amount of friction on the market, are extremely lightweight, and are simply the ultimate racing chain. Average tensile strength of 4,800 pounds. Recommended displacement: 50cc - 125cc. Weight (per 100 links): 1.9 pounds. The 420 chain has 130 links. Includes clip-style master link. Seven-day money back guarantee. Notes: The use of the Mika Metals Master Link Press Tool (sold separately) is HIGHLY recommended to press on the master link as the chains are designed not to have any slack. Non-sealed chains require more regular maintenance than sealed (O-ring, X-ring) versions and are mainly recommended for off-road use.