Head 2013 Youtek Graphene Speed Pro Tennis Racquet Novak Djokovic's previous racquet of choice, the Head Graphene Speed Pro lets you take big swings at the ball or dial back the power for easy drop shots Head Size: 100 sq. inches / 645 sq. cm Length: 27 inches Balance: 6 Points Head Light String Pattern: 18 Mains x 20 Crosses. Racquet is strung and ready to use.