A taper bushed sprocket is a sprocket where a tapered bushing is bolted into the taper bore that is machined in the sprocket. When installed this bushing is compressed onto the shaft providing a tight grip. Taper bushed sprockets have a tapered bushing bolted into a taper bore with hex head set screws instead of bolts. Martin Single Roller Chain Sprocket, Double Strand TB Bushed Solid Type A, 4.703 in Outside Dia, 60-2 Chain, 18 Teeth, 3/4 in Pitch, 4.319 in, 1-1/4 in Length Through Bore, 2012 Taper Lock Bushing, Steel