Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer for deep skin...

https://bizzmarkblog.com/is-ultherapy-fda-cleared-for-lifting-or-just-tightening/

Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer for deep skin lifting, with results peaking around 3 to 6 months. Compared to RF, which heats the skin to 40-45°C mainly for collagen tightening, Ultherapy reaches deeper levels