Adult tennis racket head size midplus racket head size 645 cm head size inches 100 sq in stringing 16 x 15 playing properties spin balance 340 mm recommended height from 155 cm weight strung 266 g weight unstrung 266 g racket balance even grip size l1 l4 frame material carbon shape oval frame profile min 28 mm frame max 29 mm length 692 cm length inches 27 technologies wilson spin effect technology wilson amplifeel technolo