Adult tennis racket head size midplus racket head size 632 cm head size inches 98 sq in stringing 16 x 20 level professional type of racket tournament racket balance 310 mm recommended height from 155 cm weight unstrung 320 g racket balance head light grip size l2 l5 frame material basalt shape oval frame profile min 20 mm frame max 25 mm length 685 cm length inches 27 series pacific bx2