Junior tennis racket head size midplus racket head size 645 cm head size inches 100 sq in stringing 16 x 19 balance 330 mm recommended height 140 155 cm weight unstrung 250 g racket balance even stiffness 67 ra grip size l0 l1 frame material graphite shape oval length 66 cm length inches 26 technologies babolat gt babolat cortex expert babolat woofer system babolat aero modular season 2013 series babolat aero additional informa