Make sure this fits by entering your model number.; T80’S ENGINE, ULTIMATE SYNC : Based on 6 years of research, T80’s patented (US8528973) Ultimate Sync tilting mechanism is designed with ITO Design Studio Germany and engineered by Sidiz and makes it possible for the chair to support your body more closely, just a fraction of an inch (3.2mm) gap from your back.
https://www.amazon.com/SIDIZ-Performance-Ergonomic-Swivel-T800HLDA/dp/B07K6BBZZK