These "seamless" socks do have a seam but it's flat and doesn't bother my son. The problem is that at the ends where the seam is tied, there is the same stiff knot of fabric as regular socks. So if thumb and pinky knots bother your child, this probably isn't for you. This is an issue for us and we've found that turning them inside out really helps some. They fit just like other socks for his shoe size, maybe a little bigger but not enough to order otherwise. I would call them medium strong. Please see photos of the inside of the sock and the knot.
12-Pack of Jefferies Seamless Sport Socks for Boys
45 Review
π Premium Prince Athletic Socks - Active Black Boys' Clothing for Top-performance
45 Review
Aminson Grip Ankle Socks: Non-Skid Slipper Crew Socks for Kids Boys and Girls - 6/12 Pairs
49 Review
Boys' Gold Toe Ultra 𧦠Tec Back Stripe Crew Socks, 5-Pack
46 Review
π Fruit of the Loom 6 Pair Cushion Ankle Boys' Clothing: Comfy and Stylish Selection for Active Boys
57 Review
Boys' Adidas Active Sports Tricot Athletic Clothing
45 Review
Waterproof Cozy-Dry Rain/Snow Pants for π§ Kids by JAN & JUL, with Fleece Lining
64 Review
Arctix Youth Pants Reinforced: Large Boys' Clothing for Active Adventures
46 Review