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

https://www.start-bookmarks.win/ultherapy-uses-focused-ultrasound-to-target-the-4-5-mm-smas-layer-for-a-deep

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