Solinco Tour Bite Soft 4 Sided Poly Tennis Racquet Strings are the best choice for the professional or advanced player seeking greater control, massive spin potential, and durability in their choice of strings. They are often used as one half of a hybrid setup, usually with a softer string like a multifilament to increase playability without sacrificing too much durability. Length: 40ft / 12m; Composition: Co-polyester monofilament; Durability: 8 out of 10; Spin: 9 of 10; Playability: 7 out of 10; Power: 6 out of 10; Comfort: 7 out of 10.