Players with long, fast strokes should love Yonex Poly Tour Fire - a round polyester monofilament that will keep your biggest strokes inside the lines. The feel is firm but nicely dampened, with a surprisingly low level of shock on off-center hits. Yonex has made this string with its unique Silicone Oil Infused Filament (SIF) Technology. This is a manufacturing process that reduces stringbed friction, enabling the strings to snap back with vicious force (resulting in heavy spin). Our playtesters were impressed by how much control this string offered and especially its tension maintenance. Although this might be a little too firm for beginners, we think it is perfect for intermediate and advanced players, especially if they want control, durability and spin.