MST® bushings are easy to install and remove. They are split through the barrel and have a taper to provide a true clamp on the shaft. They are keyed to both the shaft and the hub to help during \"blind\" installations. Martin MST Bushing, Standard, 1-3/8 in Bore Dia, 1.8555 in Small End/1.9375 in Large End Barrel Dia, 3 in Hub Dia, 2.438 in Bolt Circle, 3 in Flange Dia, 0.41 in Flange Thickness, 3 Bolt Holes, 5/16-18 x 1 in Screw, For Use With: MST® Sprockets and HP1/HCP1 Weld-On Hubs, 1.94 in Overall Length, 5/16 x 5/32 in Keyway, Steel