Ultherapy uses focused ultrasound to reach the 4.5 mm SMAS layer, which...

https://www.hometalk.com/member/254051008/alice1337254

Ultherapy uses focused ultrasound to reach the 4.5 mm SMAS layer, which standard HIFU often can’t target as deeply. RF heats skin to 40-45°C for collagen boost but doesn’t reach the same depth