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

https://technivorz.com/why-is-imaging-such-a-big-deal-in-ultrasound-skin-tightening/

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