Slightly too big for my 4 year old son but he'll grow into them. We still like them a lot. Maybe he takes them off allot because he looks down at his phone a lot and they just don't cling hard enough because they have a bit of flexso they can grow with the child. I love that. I think when he wears them to ride his bike he'll probably leave them on. Also the blue is only blue on the outside. It does not make his view turn blue. Looks like normal sunglasses from the inside out. Just what I wanted. I was afraid they would be too see through like the picture of the kid wearing them but they're not.