Adult tennis racket head size midplus racket head size 645 cm head size inches 100 sq in stringing 16 x 19 levels professional advanced type of racket all round racket balance 315 mm recommended height from 155 cm weight unstrung 315 g racket balance head light stiffness 74 ra grip size l1 l4 frame materials graphite tungsten shape oval frame profile min 23 mm frame max 26 mm length 685 cm length inches 27 technology babo