Adult tennis racket head size midplus racket head size 632 cm head size inches 98 sq in stringing 16 x 19 level professional type of racket tournament racket playing properties power balance 315 mm recommended height from 155 cm weight unstrung 300 g racket balance head light grip size l2 l4 shape oval frame profile min 20 mm frame max 20 mm length 685 cm length inches 27 technology head graphenext season 2016 series hea