Wegreeco Swim Diaper Size Large is great for baby nine months three years old weight 2040 lbs Size Small is great for baby 08 months weight 1019 lbs if the baby is thin we suggest size S Cute Prints Outer layer designed for holding solids when swim Interior mesh Soft to your baby and helpful for holding solids or poo Adjustable Swim Diapers Adjust the swim diaper size by front waist corresponding snaps Great for babies from birth up to 3 years old and great help for Mommy Package 3 pcs per set