Milwaukee Twins Front Master Cylinder Rebuild Kit The Milwaukee Twins Front Master Cylinder Rebuild Kit, engineered to surpass OEM standards, ensures a blend of reliable performance and durability. Its comprehensive kit comes with a top-grade metal piston and is designed with a precise 5/8 bore for an exact fit, guaranteeing enhanced functionality and longevity. Formerly offered under the J&P Cycles brand. Features: Meets or exceeds OEM specifications Includes metal piston 5/8 Bore Replaces OEM 45072-87