Aluminium body with cut flange. 7075 solid aluminium axle. Axle dimensions: Front: M9 x 100mm, Rear: M10 x 120mm. Holes: 32H. Sealed bearings. Flip-flop hub: Takes fixed sprocket and freewheel on opposite side. Includes: 1/8" 18T CrMo sprocket and lock ring. Freewheel sprocket available separately. Aluminium fixed sprocket available as an optional upgrade. Weight: Front: 264g, Rear: 315g.