The Wilson Enduro Pro is a high performance string offering unprecedented control and power. This string offers excellent durability and actually plays a bit on the lively side for polyester The Enduro Pro has a high modulus co-polymer (nylon) and polyester mix that gives this string a softer and more forgiving feel compared to traditional polyester strings. We would recomend this string to power players and string breakers who are searching for a string that will still provide comfort as well as durability.