Headband and Hearplug For Swimming and Fitness.
The purpose of this headband in swimming is to cover your or your kid's ears. Sometimes kids really suffer from the water coming in the ears, which can also bring infection and more serious problems.
Unless you don't want to use the proper earplugs inside your ears, the idea is to wear this Ear/Headband cover underneath the swimming cap for more efficacy and compression.
Alternatively, you can also use it for fitness, yoga and general exercises to hold up your hair while exercising.