Tecnifibre Triax Tennis String was developed for players who crave control without the stiffness of a 100% polyester string. Building off HDMX`s success, Triax is constructed of 50% polyamide fiber and 50% TPI (Thermo Polyester Improved). According to the Technilab research, Triax offers a 15% firmer stringbed when compared to a typical multifilament and a 50% increase in durability as well. At the same time, Triax is 15% more shock absorbent versus a classic monofilament string. If you love polyester firmness and control, but you have struggled with tennis elbow, Triax is the perfect string to try.