Specialties TA Aero" type outer chainring.Aerodynamic design for improved air penetration and reduced vibration.For use on triathlon and time trial bikes.Can be fitted to all brands of crankset with 130mm spacing, classic 5-spoke.For ideal shifting quality, we strongly recommend combining it with the Hegoa 11 internal or Alizé internal with a spacing of between 12 and 16 teeth.