Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer to tighten...

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

Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer to tighten skin deeper than RF and standard HIFU, which mostly warm surface layers around 40 to 45°C