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

https://fernandosgreatinsight.urbanvellum.com/posts/can-rf-tighten-skin-but-not-lift-what-does-that-mean

Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer to encourage gradual collagen tightening, with results peaking around 3 to 6 months