Wolf Tooth ZS44 Upper ZS56 Lower Premium Headset Lightweight, Strong, and Durable The headset is the part that goes through your headtube and makes it possible for you to steer properly. With an excellent headset, your bike will steer much more smoothly than before. The Wolf Tooth ZS44 Upper ZS56 Lower Premium Headset is designed to be lightweight, strong, and durable. It has three levels of industry-leading custom sealing to protect bearings from the elements and prolong the life of the headset. This headset has a Zero Stack 44mm upper and a Zero Stack 56mm lower. Features O-ring seal prevents water intrusion around the steerer tube Made from aircraft-grade 6061 aluminum Made in the USASPECIFICATIONSTechnical Description ZS44/ZS56Top Type ZS - Zero Stack Top Head Tube Inside Dia. 44mm Stem Clamp Dia. 1-1/8"Top Stack Height-Top Bearing Type Premium Stainless Steel Bearing Bottom Type ZS - Zero Stack Bottom Head Tube Inside Dia. 56mm Crown Race Seat Dia. -Crown Race Type Aluminum, Dual-Lip Seal Bottom Stack Height-Bottom Bearing Type Premium Stainless Steel Bearing Material6061 Aluminum Weight129 - 136g Wolf Tooth Headset Fit Guide To figure out which headset you need for your particular frame and fork, see Wolf Tooth's Headset Fit Guide by clicking HERE. | Wolf Tooth Components | Zs44 Upper Zs56 Lower Premium Headsets Olive