My baby is 5 months old and the strap fits her head perfectly on the tightest Velcro "setting." Because the frames and lenses are wide, they do not annoy her and because they're well-fitting, she leaves them completely alone. She used to squint and look uncomfortable when the sun shined on her, but now she just looks comfortable. I like that they have UV protection, too. They look really high quality. I like that she will be able to wear them for a couple of years because of that strap being adjustable. Great purchase!