Yonex Poly Tour Air is composed of an elastic HR polymer addition, but it still maintains the regulated responsiveness and crisp feel of polyester monofilament. A control string with remarkable shock-absorption is the end product. This is actually the softest poly-based string that Yonex has tested. Additionally, this string offers excellent snapback for increased ball rotation. Big hitters should adore this string if they're searching for a control string with above-average comfort.