Contains right and left crankshaft bearings (contains outer seals for all 2-stroke engines). Either Koyo or Nachi Bearings (precision Japanese crank bearings)Reduce crank pin wear with our crank seals! Our seals are designed with a carbon/fluorocarbon sealing lip to reduce "dry start" friction Quality design and construction of every All Balls piece meets the toughest standards and conditions - from daily commuting to full-on racing, all older bearing and seal designs are upgraded to the best and latest specs and designs.