Ultherapy uses focused ultrasound to target the 4.5 mm SMAS layer, unlike RF...

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

Ultherapy uses focused ultrasound to target the 4.5 mm SMAS layer, unlike RF which heats tissue around 40 to 45°C without deep reach. Standard HIFU often doesn’t go as deep as Ultherapy or is less precise