Multifilament Synthetics. Optimal playing string providing superior shock absorption and gut-like playability.NXT is Wilson's premier playability string. If you're looking for comfort, feel, and playability, you're looking for NXT. It's constructed with polyurethane, the same material used for cushioning in your shoes, so this string is a great choice even if you suffer from arm pain.Closest playing string to natural gut, No.1 rated synthetic gut string for playability and comfort (USRSA), expands sweetspot by 10%, reduces vibration up to 74% vs. traditional synthetic gut, patented construction using Dupont Xycromicrofibers.