Adult tennis racket head size oversize racket head size 658 cm head size inches 102 sq in stringing 16 x 19 level advanced type of racket all round racket balance 330 mm recommended height from 155 cm weight unstrung 270 g racket balance even stiffness 70 ra grip size l0 l4 frame material graphite shape oval length 685 cm length inches 27 technologies babolat woofer system babolat hybrid season 2017 series babolat game babola