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

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

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