Keter Kid's Poly/Cotton Tzitzis with Round Neck and 1 hole for the tzitzis strings. Size 2 measures approximately 12 inches long from the shoulder to the bottom of the garment, size 3 is 14 inches long, size 4 is 16 inches long, size 5 is 18 inches long, and size 6 is 19 inches long.
I'm giving a little unasked for advice, check all tzitzis to be sure there's no defect in the knots. I was surprised to find some of my son's that weren't kosher (not saying it was from this specific product). I'm not saying these are defective, just pointing out it's important to check this type of product.