Acros az 44 zs44 30 lower headsetperfect for updating your existing lower headset, this headset gives you a robust interface. It features a durable aluminium construction, which makes it capable of handling all the intensity that's associated with all day epics in the mountains and long distance road bike journeys. Coming equipped with stainless steel bearings, this lower headset gives your bike an extra layer of 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 use road, mtbsteerer diameter 1 1 8headset type semi integratedpart number 2202601r6sbuy acros components from chain reaction cycles, the world's largest online bike store.