ISO 10823:2004 gives guidelines for the selection of chain drives, composed of a roller chain and sprockets conformant with ISO 606, for industrial applications. The selection procedures and chain ratings it describes provide for roller chain drives operating under specified conditions with a life expectancy of approximately 15 000 h. Owing to the wide variations in loading characteristics, environmental conditions and achieved maintenance, it is desirable that the supplier of the chains and sprockets be consulted to ensure that the performance of the product meets the requirements specified both by the user and by this International Standard.