Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer for a deeper...

https://martinsultimatecolumns.quillnesty.com/posts/what-does-mfu-v-stand-for-in-ultherapy

Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer for a deeper lift, with results peaking around 3 to 6 months. In comparison, RF heats tissues to 40-45°C, promoting collagen but with a gentler lift