Dear Caro3, I googled for you and found it at 3M: From 5 years.
https://www.3mschweiz.ch/3M...
But if it's not too big, I see no reason why the child shouldn't be able to wear the hearing protection under the age of 5.
Hello Nicoleba
From my point of view, definitely too big for the very little ones. I would rather recommend the Baby Banz - our daughter loved wearing it. Baby Banz hearing protection
Greetings
highfish