Acros az 44 zs44 28.6 lower headsetengineered to provide a smooth rotatable interface between your bike's fork and headtube, this lower headset gives you dependable steering performance. It features a hard wearing aluminium construction, which makes it more than capable of handling all the abuse that's associated with shredding the mtb trails and clocking up the miles on your road bike. Coming complete with stainless steel bearings and an r3 seal, this is the perfect upgrade for dependable performance 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 2202605r6sbuy acros components from chain reaction cycles, the world's largest online bike store.