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

https://wiki-saloon.win/index.php/Does_Ultherapy_Hurt_and_What_Affects_Comfort%3F

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