I bought this hat in a size 1-3 and also a size 4-6 for my 21 month old son who has a huge head (99th percentile). Hat 1-3 fit my son but he was tight and there was no room for growth. Size 4-6 was too big for him but stayed on his head and wasn't big enough to fall off and close his eyes. In the end we kept the 4-6 hat. I love the gray and neon green colors. It's fun but not too much and goes with everything he wears. Size Advice: Size 1-3 tag says it runs small for youth. Size 4-6 years is…