One replacement 1-3/8" X 21 spline clutch hub for Italian slip clutches, replaces 140 mm diameter clutch hubs that use two friction disc, will not fit 4 friction disc units. These are new OEM clutch hubs. Designed to mount via two cinch bolts. These hubs will fit most Italian 140mm slip clutches. Specifcations: OD: 140mm or 5.51" ID: 35mm (1-3/8") with 21 splines Fits Italian FD1 Series Slip Clutches