Abstract: A racket string filament having in cross-section a first face and a second face, formed back to back, is strung in the frame of a racket such that the first face is exposed only on one side of the racket and the second face only is exposed on the other side of the racket, thus forming a first uniform hitting surface on one side and a second uniform hitting surface on the other side. The hitting surfaces thus formed by the various faces cause a ball, when stroked, to form a trajectory which will be influenced greatly by the type of hitting surface used, and will impart spin or English to the moving ball. In one embodiment, the cross section of the first face is convex in shape and the cross section of the second face is flat or concave in shape.