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

https://www.cast-bookmarks.win/ultherapy-uses-focused-ultrasound-targeting-the-4-5-mm-smas-layer-stimulating

Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer for deep skin tightening, with results peaking around 3 to 6 months. RF heats the skin at 40 to 45°C to boost collagen more superficially and often requires multiple sessions