Wolf Tooth Components Premium Bicycle Headsets Espresso 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 together as a set. Enduro stainless steel sealed bearings included 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. For forks with carbon steerer tubes you will need a compression plug (sold separately). (Never use a star nut on a carbon steerer tube). Upper assembly features: Ultralight stem cap with integrated spacer plus an aluminum bolt and a star nut. 6 mm stack height top cover only O-ring seal prevents water intrusion around steerer tube. Custom-molded upper lip seal provides additional protection for upper bearing. Lower assembly features: Custom-molded dual-lip seal on the crown race protects lower bearing in the toughest conditions. All components precision machined in-house at Wolf Tooth from aircraft grade aluminum to ensure the highest level of quality. Service and additional parts available. Tech Specs Weight: 55-58gMaterial: 6061 aluminum Bevel Angle: 36 x 45 degrees Stem Cap Bolt Torque Spec: 2-3 Nm with light grease on threads only Made in the USA