Wolf Tooth MK0 IS42 Upper Headset The Lightest Stack in the Lineup MK0 items represent a refined approach to component engineering, and the MK0 IS42 Upper Headset is no exception. Machined out of aircraft-grade 6061 aluminum with a labor-intensive CNC process, this upper delivers the shortest possible stack height while maintaining the strength, sealing, and performance found in Wolf Tooth's Premium Headset line, all in a striking new Shadow Gray finish that shows off the visible machine paths of the MK0 design. Features Ultra-short 4mm stack height for the leanest cockpit setup possible44% lighter than the standard non-MK0 design, with no compromise in strength or durability Premium stainless steel Enduro bearing for smooth, long-lasting rotation Aircraft-grade 6061 aluminum construction, machined in-house in Wolf Tooth's Minnesota shop Three levels of custom sealing to protect the bearing from water, dirt, and debris Exclusive Shadow Gray anodized finish with visible machine paths unique to the MK0 line Includes MK0 Flat Stem Cap, star nut, MK0 top cap, shim washers, and split ring for a complete upper assembly SPECIFICATIONSIntended Use Road, Gravel, MTBS. H. I. S. Designation IS42/28. 6Stack Height4mm Bearing Enduro stainless steel Material6061 Aluminum Compatibility Frames with molded-in internal bearing cups, 42mm head tube inner diameter (not compatible with Specialized mountain bikes or Campagnolo Hiddenset)Included MK0 Flat Stem Cap, star nut, MK0 top cap, shim washers, split ring | Wolf Tooth Components | Mk0 Is42 Upper Headset Shadow Gray