Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer for deep skin...

https://www.slideserve.com/gierrepjfu/which-areas-can-ultherapy-treat-neck-brow-d-colletage-explained

Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer for deep skin tightening, with results peaking around 3 to 6 months. RF heats the skin at 40 to 45°C to boost collagen more superficially and often requires multiple sessions