Ultherapy uses focused ultrasound to target the 4.5 mm SMAS layer, reaching...

https://www.bookmarkpage.win/ultherapy-uses-focused-ultrasound-to-target-the-4-5-mm-smas-layer-promoting-2

Ultherapy uses focused ultrasound to target the 4.5 mm SMAS layer, reaching deeper than standard HIFU, which works around 1.5 mm. RF heats skin to 40-45°C to stimulate collagen more superficially