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

https://highstylife.com/thermage-vs-10therma-are-they-both-monopolar-rf/

Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer for a firmer look, with results peaking around 3 to 6 months. Unlike RF, which heats skin to 40-45°C mostly for surface tightening, Ultherapy reaches deeper layers