Uses water-repellent fabric (not waterproof). It's a regular to slightly thin fabric, with a light stiffness but is soft. Length: Approximately 14cm Width: Approximately 14.5cm Elastic: 12cm / 18cm I'm not sure about the target age since I don't have any young children, but I think it could be used as an arm cover for children up to preschool age... Please judge based on the size (^_^;)