Adult tennis racket head size oversize racket head size 658 cm head size inches 102 sq in stringing 16 x 19 level advanced type of racket all round racket balance 320 mm recommended height from 155 cm weight unstrung 285 g racket balance head light grip size l0 l5 frame material graphite shape oval frame profile min 23 mm frame max 26 mm length 685 cm length inches 27 technology head graphene touch season 2017 series hea