Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer, stimulating...

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

Ultherapy uses focused ultrasound targeting the 4.5 mm SMAS layer, stimulating collagen deep beneath the skin. Results build gradually, peaking around 3 to 6 months. Compared to RF, which heats tissue to 40–45°C, Ultherapy reaches deeper layers