Adult tennis racket head size oversize racket head size 677 cm head size inches 105 sq in stringing 14 x 16 level beginner type of racket comfort racket balance 340 mm recommended height from 155 cm weight unstrung 270 g racket balance even grip size l0 l4 frame material graphite shape oval frame profile min 23 mm frame max 25 mm length 687 cm length inches 27 series prince premier