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. External cups press into headtube. 1.5" - 1 1/8" Tapered steerer tube required Includes top and bottom ZS56 assemblies. Sealed black oxide bearings Carbon-friendy compression ring captured in top cover, keeping shims in place Interlok spacer compatible