yes, it's the flare rt. the setup on my ultimate is this mount from bontrager and this seat post clamp off amazon
i also have this bontrager mounton another bike. it's way cheaper, but was impossible to find when i was trying to find a mount.
I use this one. But more solid than the Garmin one: Tuson Varia Mount for Garmin, Varia Rtl510 Radar Mount, Varia Rear Seatpost and Saddle Mount. https://www.amazon.com/dp/B08N154BBY/ref=cm_sw_r_apan_i_0PQN0G8K1ZAE8EGDM3SY?_encoding=UTF8&psc=1
Tuson Varia Mount - https://www.amazon.com/gp/product/B08N154BBY/