Nothing from EC, just repacing the part. When I had my original C3 next to the EC pulley i noticed three obvious differences. First the C3 pulley slides on and off smoothly while the EC pulley seamed to be a tighter fit and went on in rough steps, this could result in the EC pulley being slightly cocked. Second the C3 pulley arms are made of a much stiffer metal then the EC pulley, giving the C3 pulley more rigidity in holding and returning to the original spacing. Third, the materail used by EC did not rust, my early C3 pulley rusted up quickly after install.