Junior tennis racket head size oversize racket head size 677 cm head size inches 105 sq in stringing 16 x 19 levels beginner advanced type of racket all round racket playing properties control power balance 305 mm recommended height 140 155 cm weight strung 255 g racket balance head light shape oval frame profile min 20 mm frame max 20 mm length 66 cm length inches 26 season 2017 player roger federer colours black red a