Carboys are rigid containers primarily used for transporting liquids, often water or chemicals. In laboratories, the containers are usually made of plastic, though some are still made of ferric glass or other shatter-resistant glasses. With a high chemical resistance and opaque exteriors to block ultraviolet light, the carboys store large quantities of liquids, such as solvents and deionized water, that will remain unaltered. Polypropylene carboys are autoclavable for easy sterilization.