Acros ah 44 ec44 40 lower headsetproviding a rotable interface between your bike's fork and headtube, this lower headset gives you smooth and dependable steering performance. It features a tough aluminium construction, which makes it able to handle the increased pressure from road racing or shredding the mountain bike trails. Acros has also equipped this lower headset with stainless steel bearings for an extra layer of durability as well as an r3 seal which protects it against corrosion.features headset material aluminium bearing material stainless steel use road, mtb steerer diameter 1.5 headset type conventional cup skirt 44mm cup skirt length 10mm total stack height 12.8mm part number 5002601r1s weight 62g approxbuy acros components from chain reaction cycles, the world's largest online bike store.