Acros az 44 zs44 28.6 block lock upper headsetperfect for updating your existing upper headset interface, this headset features a tough aluminium construction. This makes it capable of handling all the intensity that's associated with long distance rides on your road bike and all day epics on your mtb. Allowing your fork's steerer to rotate inside your frame's headtube, this upper headset is equipped with stainless steel bearings. This gives it an extra durability, while its r3 seal allows it to perform in all weather conditions. Features headset material aluminium bearing material stainless steel seal material r3 metal reinforced rubber steerer diameter 1 1 8 headset type semi integrated cup skirt 44mm cup skirt length 7.7mm total stack height 21.9mm part number 5102605r1s weight 81g approxbuy acros components from chain reaction cycles, the world's largest online bike store.