Ultherapy uses focused ultrasound at a 4.5 mm depth to target the SMAS layer,...

https://cristiansinterestingthoughtss.opalvector.com/posts/how-long-do-ultherapy-results-last-is-the-12-to-18-months-claim-real

Ultherapy uses focused ultrasound at a 4.5 mm depth to target the SMAS layer, promoting gradual skin tightening with peak results around 3 to 6 months