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

https://www.third-bookmarks.win/ultherapy-uses-ultrasound-energy-targeting-the-4-5-mm-smas-layer-to-stimulate

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