JL Velo Tribal Kids Jersey. Made from the same awesome vertex fabric that Mom & Dad's jersey is made with. Vertex is a woven, recycled fiber with more stretch than other woven fabrics! And, it has a high UPF rating. Think of UPF as SPF for fabrics – i.e. Great sun protection! Kids Sizing is Small Medium, and Large only: - Kids Small typically fits big 2 year olds to small 4 year olds. - Kids Small typically fits big 3 year olds to small 6 year olds. - Kids Large typically fits big 5 year olds to small 9 year olds.