Adult tennis racket head size midsize racket head size 632 cm head size inches 98 sq in level professional type of racket tournament racket balance 315 mm recommended height from 155 cm weight unstrung 295 g grip circumference 112 114 mm racket balance head light grip size l4 frame material graphite shape oval length 685 cm length inches 27 technology head graphenext season 2016 player andy murray series head radical special