For a racquet, there are so many factors to affect its performance: 1. Whole weight (2U,3U,or 4U); 2. Balance point (headlight, headheavy); 3. Flexibility of the shaft (stiff, flex); 4. Kick point of the shaft as some manufacturer concerned (I don't know it exactly); 5. Shape of the frame (classic oval shape, isometric, Y shape) or the sweet point; 6. Width of the frame; 7. Grip size (G3, G4); 8. String style (BG 65, 66, 70....); 9. String tension. But I have heard so many opposite opinions on these factors. Now I'm just puzzled by those factors, Which ones are really important for the performance and how do they work?? For the following performances: 1. power: smash, clear, or drive. 2. control: direction control, power control. 3. maneuverability: when you need quick reflection in the game. 3. comfort: make you play for long time without hurt on the arm or wrist. I really don't know how to describe this one, but I think it's really important. Because some headheavy racquet, maybe you can smash harder than usual, after a game and you find you can not even clear in the next one. 4. analyze the technics and the racquets, which factor benefit the wrist player, which one for the arm styles??