I just found a few shimano SX brake levers. To start with i thought they were shimano DX, but they have SX written on them?. They look and operate exactly the same as a dx, (they have the little plastic bit that pushes the cable forward and also the adjusting mechanism you turn to widen the lever). Does anyone know much about these? The ones i found are chrome, so i am not sure if the diffrence between the DX and SX is that the SX may be steel rather than alloy, anyone know?