Launched at the end of 2021, the KIZUNA D66 Lusty Duratech / Soft - 0.66 mm is the newest string in the KIZUNA string family. With a diameter of 0.66 mm, it belongs to the midfield of the KIZUNA string series. When we received the KIZUNA D66 strings directly from Japan, the KIZUNA team told us: Especially for hard hitters! Of course we wanted to know exactly how "lusty" the new KIZUNA D66 Duratech string really is and our testers from the BADLAB team strung the D66 on their personal rackets for a long-term test with great expectations.