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

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