Abstract: A rail (22?, 22?) for the vertebra of the blade rubber (10) of a windscreen wiper has over its entire length a substantially constant cross-section deviating from a rectangular cross-section. The rail (22?, 22?) has a moment of inertia I, has a particular width and has a particular surface area. The moment of inertia I is larger than the moment of inertia of a rectangular wire with a same width and a same surface area. The cross-section has a circumference exhibiting both convex and concave portions. The rail is made of a drawn or rolled steel wire. The typical cross-section of the rail allows to have a stiffer structure without increasing the weight.