Ultherapy uses ultrasound to target the 4.5 mm SMAS layer, making it popular...

https://sophiasbestchat.capitaljays.com/posts/does-ultherapy-hurt-and-what-affects-comfort

Ultherapy uses ultrasound to target the 4.5 mm SMAS layer, making it popular for lifting deep tissue without cutting. RF heats skin to around 40-45°C to boost collagen, great for mild tightening