Ultherapy uses focused ultrasound to target the 4.5 mm SMAS layer for a deeper...

https://kameronssplendiddigests.zenbloomer.com/posts/does-ultherapy-help-with-skin-texture-or-only-lifting

Ultherapy uses focused ultrasound to target the 4.5 mm SMAS layer for a deeper lift, unlike RF that heats skin at 40 to 45°C mainly for surface tightening. Standard HIFU varies in depth but often hits shallower layers