Reed style breather. Will tackle problems with OEM engines as Oil Carry Over (blowing oil out of the breather system), a common problem for years. Usually at sustained high speeds and worse with big inch engines. This problem can still be present in OEM Twin Cam engines. S&S designed this aluminum crankcase breather valve containing four steel reed valves, which effectively prevents wild turbulence in the cam chest and rocker boxes. Air and oil mist can escape from the crankcase, but is not allowed to re-enter. Any oil blowing out of the crankcase breather is stopped. A slight increase in horsepower (one to two HP) and torque can be expected. The breather valve is installed over the pinion shaft, inside the pinion bearing bore, and retained between the bearing outer retaining ring and the oil pump. Note: Will not fit TCB (Softail) models. 

Fits: > 99-02 Twin Cam (excl. Softail) with OEM cases and oil pump