Junior tennis racket head size midplus racket head size 645 cm head size inches 100 sq in stringing 16 x 19 level professional type of racket tournament racket balance 320 mm recommended height from 155 cm weight unstrung 300 g racket balance head light grip size l2 l5 frame material basalt shape oval frame profile min 22 mm frame max 25 mm length 695 cm length inches 27 series pacific bx2