This International Standard specifies the principal dimensions of grooved pulleys for classical V-belts (sections Υ, Ζ, A, B, C, D and E) and narrow V-belts (sections SPZ, SPA, SPB and SPC) specified in the terminology system based on datum width. It is important that narrow belts are not used with pulleys uniquely designed for classical belts, and, on the other hand, that multiple belt drives are not used with joined V-belts.