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

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

Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer for natural lifting, with results peaking around 3 to 6 months. Compared to RF, which heats skin to 40-45°C to stimulate collagen superficially, Ultherapy goes deeper for firmer support