The round rewinder belt is the drive component that, in Italiana Macchi Mach 4000 electronic labelling scales, drives the label backing-paper rewind unit inside the built-in printer. It is an Italian-made round transmission belt in elastic synthetic material, sized to match the exact drive pitch required by the rewinder motor.

With the daily use typical of butcher shops, delicatessens and fresh-food counters, the belt gradually loses elasticity or starts slipping: when the label roll is no longer rewound evenly or the motor spins without pulling the paper, it is time to replace it.