The Thule railing clamps no. 415 shown above differ from others clamps in that the bars slide through the clamps; they can therefore only be used with steel bars. If choosing longer bars it is essential to check that the overall width of the load will not be wider than the vehicle, excluding the wing mirrors. It is sensible if the bars do not protrude more than 50% of the distance between the roof rails and the widest point of the vehicle (excluding the wing mirrors).