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

https://beckettsexcellentjournal.cloudhinter.com/posts/secret-rf-vs-thermage-what-is-the-real-difference

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