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

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 a firm lift, with results peaking around 3 to 6 months