Acros AZX-589 HeadsetSpecifically made to meet the extra demands of electric mountain bikes (E-MTBs), the Acros AZX-589 Headset delivers super-smooth performance, so you can enjoy responsive steering as you attack the toughest trails. This tapered headset adopts the larger 66mm lower headtube sizing standard, which is becoming increasingly popular with E-MTB frames due to the extra strength that this thicker lower headtube provides.Features: Headset Type: Semi-Integrated ZS56/66 Steerer Compatibility: 1.1/8" - 1.5" tapered Cone Race: 39.8mm Upper Cuper inner Diameter: 56mm Upper Cup Outer Diameter: 62mm Lower Cup Inner Diameter: 66mm Lower Cup Outer Diameter: 76mmmBuy Acros Components from Chain Reaction Cycles, the World's Largest Online Bike Store.