Wolf Tooth Premium Headset - EC34/28.6 Upper 16mm Stack BlackWolf Tooth Premium headsets are machined out of aircraft grade aluminum and feature high end bearings made by Enduro. They are engineered to use the largest possible ball size and are filled with high pressure waterproof lubricant. A pair of dual lip seals ride in micro grooves to keep out water and debris. Stainless steel bearings provide unparalleled corrosion resistance Highly recommended if your headset will be exposed to wet conditions or sweat