Ultherapy uses focused ultrasound targeting the 4.5mm SMAS layer to promote...

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

Ultherapy uses focused ultrasound targeting the 4.5mm SMAS layer to promote collagen over 3 to 6 months, making it a top choice for deep skin tightening