These simply work. I tested each side to ensure they block noise before trusting them on my child (low tech way with a plug in one ear and covered my other ear with each side to judge the nose reduction).
Next I made sure they didn't exert to much pressure on his head. He likes them and understands how they work so I'm happy.
I won't trust these for any potentially damaging noise but these are great for riding our 125cc mini Jeep to protect his little ears from the constant done of the motor.