A metric 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 Simplex Roller Chain Sprocket, Metric Solid TB Bushed Type B, 12.7 to 41.28 mm Bore Dia, 121.23 mm Outside Dia, 10B-1 Chain, 22 Teeth, 15.88 mm Pitch, 111.55 mm, 76 mm Hub Dia, 25.4 mm Length Through Bore, 1610 Taper Lock Bushing, Steel