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

https://hectorsmasterinsight.novacrestiq.com/posts/thread-lift-migration-how-common-is-it-and-what-does-it-look-like

Ultherapy uses focused ultrasound to target the deep 4.5 mm SMAS layer, encouraging natural collagen over 3 to 6 months for gradual lifting. Compared to RF, which heats skin surface to around 40-45°C, it's deeper but less immediate