MEDIUM - The abrasive compound is not retained inside the sponge but is continuously applied to the work surface, providing a constant layer of lubricated abrasive between the surface and the foam polishing pad.
Rupes 1" Foam Polishing Pads

MEDIUM - The abrasive compound is not retained inside the sponge but is continuously applied to the work surface, providing a constant layer of lubricated abrasive between the surface and the foam polishing pad.