Adult tennis racket head size midsize racket head size 581 cm head size inches 90 sq in stringing 16 x 19 level professional type of racket tournament racket balance 315 mm recommended height from 155 cm weight unstrung 339 g racket balance head light grip size l1 l4 frame material graphite shape oval frame profile min 17 mm frame max 17 mm length 686 cm length inches 27 technology wilson amplifeel technology season 2014