The organic cotton option is available in two sizes: extra small and small. Our materials and sizing options are restricted due to regulations of the United States Consumer Product Safety Commission. Current regulations require that: 100% cotton pajamas for babies 9+ months of age must be treated with flame retardants This means that 100% cotton pajamas for babies under six months are not required to be treated with flame retardants. The extra small and small Zipadee-Zips fit babies under the age of nine months, so they are not chemically treated. Each organic Zipadee-Zip is made from 100% organic cotton ring-spun yarn.