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. The 420 chain has 130 links. We HIGHLY recommend the use of a master link press to press on the master link as the chains are designed not to have any slack. 420 chains fits the Cobra 50 (stock), all 65cc bikes, and ONLY the Kawasaki for the 85.