Acros ah 49 ec49 3040 lower headsetready for intense road and mountain use, this lower headset features a tough aluminium construction. This makes it capable of handling all the aggressiveness 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 lower 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 use road, mtbsteerer diameter 1.5headset type conventionalpart number 1502601r4sbuy acros components from chain reaction cycles, the world's largest online bike store.