Abstract: A tennis racket strung with a string grid, each strand of which has a cross-section defining a polygon with concave sides thus providing the grid strands with longitudinally extending concave surfaces which meet to form longitudinally extending sharp edges. At each junction between the strands of the string grid the sharp edges contact each other only at four sharply defined spaced points thus locking the strands to each other at each junction. In weaving the string grid substantial rectilinearity of the concave surfaces and sharp edges of the strands is maintained.