My son 12 years old is breaking the strings more than once a week now, he is trained for about 10 hours for week, the main strings broke always in the same position in the center and between the third and the fifth cross string from top. The strings are heavy notched already after 2 hours of play if I move the crosses they stick back in the notched position. Mains are moving a lot. The racquet is a Wilson Kfactor Kpro Team FX and will stay the same for another year. The strings actually used are Weisscannon Explosive in the mains @ 51 and the crosses are MSV Evo Hex @ 48. I change the crosses with Weisscannon Scorpion 1.22 (always @ 48) to try to have a bit more life but with this string in the crosses the ball stay on the racquet the shoot are much more shorter. He has tested different setup full Explosive about same life time, full MSV Evo Hex at @ 49/47 he has the feeling that the shoot is unpredictable. Evo Hex on mains and Explosive on crosses he don't like the feeling and he found also this setup unpredictable. What I'm looking for ? I'm looking for a strings with a life of about 20 hours before breaks or go dead so I can restring a racquet every 2 weeks and not 4-5 days like now, quite powerful and not expensive like rpm blast or alu power. Could you please help me to get the right string ?