Cane Creek 40-Series ZS(Zero Stack) assemblies feature press-in cups with bearings inside the frame. The 40-Series is the workhorse of Cane Creek"s headset line-up. Representing the balance of performance, durability and value, the series incorporates all the features necessary for a robust, lightweight, long-lasting headset.Item SpecificationsColorBlackMaterialAL-6061Crown Race39.7Bearing TypeBlack Oxide SealedDefined ColorBlackS.H.I.S UpperZS44S.H.I.S LowerEC44S.H.I.S. Clamp Diameter28.6