They also protect against the sun’s harsh rays and insects. Have your little one wear them while learning to crawl to stay clean and to protect his or her knees. Ideal for newborns to 6 years of age. Protect baby’s knees when crawling and from exposure to cold sun and insects. Also keeps little legs warm during diaper changing. Can be worn on the legs or arms. Size: One size approximately 12 inches long. Can be worn on entire leg for babies and up to the mid-thigh or knees for toddlers. Made out of cotton spandex polyester.