Ultherapy uses focused ultrasound to reach the 4.5 mm SMAS layer, which...

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

Ultherapy uses focused ultrasound to reach the 4.5 mm SMAS layer, which standard HIFU often can’t target as deeply. RF heats skin to 40-45°C for collagen boost but doesn’t reach the same depth