We got beizi posture correctors for our kids (10 and 14yo) to prevent slouching and improve posture. They are tall and they do slouch.
There are different opinions on how long/often to wear it, especially if we take, say, a child 10 years old, teenager 18yo, or adult 30yo.
The correctors definitely work, results are noticable, and children don't mind to wear it.
Are there any general recommendations, which could be applied to children in terms of how often to use it and how long?