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

https://scarlettssuperbnews.inkharbory.com/posts/what-is-the-safest-way-to-compare-clinics-offering-ultherapy-in-singapore

Ultherapy uses focused ultrasound to target the 4.5 mm SMAS layer deep under your skin, encouraging natural collagen over 3 to 6 months. RF heats the surface to about 40 to 45°C for a quicker, milder firming effect