Check the listing for details. Wolf Tooth Premium ZS Headset - Zero Stack 44mm Upper, Aluminum, Sealed Bearings. Condition: New. Listed at 69.90 USD. Wolf Tooth headsets are machined here in our Minnesota shop with aircraft-grade 6061 aluminum. They are designed to be lightweight, strong, and durable. 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. Premium Headsets with Enduro stainless steel bearings have a lifetime warranty on the bearings. Compatibility Any frame that uses ZS (Zero Stack) headsets with 44mm upper and 56mm lower head tube inner diameter. Uppers and lowers sold separately. Enduro stainless steel sealed bearings included on both the upper and lower. Upper headsets ship with a star nut which can only be.