Whether we are building from the frame up or just replacing our headset, the Wolf Tooth EC34/28. 6 Premium Upper Headset is one of our favorites for both style and performance. Wolf Tooth headsets come in an array of colors to match any bike and feature premium enduro stainless steel bearings, multiple stack heights to choose from, and a lifetime warranty to give us peace of mind. The three different stack heights consist of a 5mm, 15mm, or 25mm top cover and a 10mm cup. This headset is only the upper portion of the headset and requires the lower part to be purchased separately. A star nut is included, which is only to be used with steel and aluminum steerer tubes.