ISO 8419:2003 specifies, for narrow V-belts of cross-sections 9N/J (for pulley grooves of effective width 8,9 mm), 15N/J (for pulley grooves of effective width 15,2 mm) and 25N/J (for pulley grooves of effective width 25,4 mm), the standard effective lengths, the tolerances on effective lengths, the centre distance variations, the conditions for measuring the effective length and the centre distance variation, and the designation and marking.