Ultherapy uses focused ultrasound to target the 4.5 mm SMAS layer deep under...

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

Ultherapy uses focused ultrasound to target the 4.5 mm SMAS layer deep under your skin, encouraging natural collagen over 3 to 6 months. Compared to RF, which heats skin to 40-45°C mainly for surface tightening, Ultherapy reaches deeper layers