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

https://mighty-wiki.win/index.php/Why_Do_Some_People_See_No_Change_After_HIFU%3F

Ultherapy uses focused ultrasound to target the 4.5 mm SMAS layer deep under your skin, stimulating collagen over 3 to 6 months for gradual lifting. Compared to RF, which heats the skin at 40 to 45°C for surface tightening, Ultherapy reaches deeper layers