Wolf Tooth headsets are machined here in our Minnesota shop with aircraft-grade 6061 aluminum. They are designed to be lightweight, strong, and durable. Performance Headsets with Enduro black oxide bearings have a one-year warranty. Our headsets have three levels of industry-leading custom sealing to protect bearings from the elements and prolong the life of the headset. Available in a variety of colors. These ZS headsets are for frames with internal bearing cups that are pressed into the frame. Compatibility - Any frame that uses ZS (Zero Stack) headsetswith 44mm upper and 56mm lower head tube inner diameter - Uppers and lowers sold separately. - Enduro black oxide steel sealed bearings inlcuded on both the upper and lower. - Upper headsets ship with a star nut which can only be used on forks with steel or aluminum steerer tubes.