Adult tennis racket head size midplus racket head size 645 cm head size inches 100 sq in stringing 16 x 19 string tension 23 25 kg level advanced type of racket all round racket balance 340 mm recommended height from 155 cm weight unstrung 255 g racket balance even stiffness 70 ra grip size l0 l4 frame material graphite shape oval frame profile min 23 mm frame max 26 mm length 685 cm length inches 27 technologies babolat