Highly polished sealed angular contact premium bearings ensure smooth operation CNC machined AL6061 top cover is sealed to keep moisture and grit away from the bearings CNC machined AL7075 crown race protects the lower bearings and fork AL6061 top cap, forged stainless steel bolt, and star nut ZS44/28.6|EC49/40 Black 28.6mm 44mm/49mm 40mm 12.7mm Top/12.3mm Bottom 45?/45? 1-1/8` to 1.5`UPC/EAN/GTIN: 888571050934