Adult tennis racket head size midplus racket head size 645 cm head size inches 100 sq in stringing 16 x 19 16 x 16 level advanced type of racket all round racket balance 345 mm recommended height from 155 cm weight unstrung 255 g racket balance even grip size l0 l5 shape oval frame profile min 21 mm frame max 27 mm length 68 cm length inches 27 technology head graphene season 2015 series head ultimate speed additional inf