Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer deep under...

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

Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer deep under your skin, reaching where threads or RF can’t, for a natural lift. RF heats the skin to 40–45°C, boosting collagen closer to the surface