For external gear systems, 21-27 gears. Crank arms made of aluminium, sprocket-wheels made of steel. Mounted chain guard. Fits bicycles with square tapered spindles and 124.5 mm crankshaft length. Number of sprocket-wheel teeth: 28-38-48. Crank arm length: 170 mm. Pedal thread: ½″. Fits Trekking, Hybrid, City, Sport bikes and more.