OCTAFORCE V-belt pulleys are solely used for transmitting power between two parallel axels. The most notable difference between a v-belt pulley and other types of pulleys (round belt, flat, etc.) would be the DIMENSIONS of the groove or grooves located around the circumference of the pulley; these grooves direct and gain traction on a v-belt.OCTAFORCE Standard pulleys are pulleys that have traditional dimensions, with one or multiple grooves, which mate with classic, small-engine, and hexagonal-style v-belts