ISO 17396:2014 specifies the principal characteristics of synchronous endless and open belts and pulleys of the profile systems T and AT for use in synchronous belt drives for mechanical power transmission and where positive indexing or synchronization can be required. The principal belt and pulley characteristics include nominal belt tooth dimensions, belt tooth pitch spacing, belt length and width dimensions, belt length measurement specifications, pulley groove dimensions and tolerances, pulley diameter and width dimensions and tolerances, and pulley quality specification.