Milwaukee Twins Master Cylinder Rebuild Kit For Harley Big Twin / Sportster The Milwaukee Twins Master Cylinder Rebuild Kit is engineered for top-tier performance, meeting or surpassing OEM specifications. This kit provides all necessary components to fully restore your motorcycle's braking power with confidence. Formerly offered under the J&P Cycles brand. Features: Meets or Exceeds OEM Specifications Includes Metal Piston Replaces OEM 42374-82A