a sleeve that has the shape seen in the longitudinal direction that deviates in cross section and / or has an outside diameter that changes from a shape with a rotational symmetry to a shape with a non - rotational symmetry and has a ridge extending at least a portion of the length of the sleeve to form ledges between the ridge and adjacent curved surfaces . a method for manufacturing the sleeve includes inserting a workpiece in a die having the desired contour for the outer surface of the sleeve , heating the material and subjecting the material to internal pressure to deform the workpiece into the contour of the die to form the sleeve .