New improved optional interchangeable impact discs allow you to adjust your volume and choose your feel in conjunction with the F2 pedal (sold separately). A pack of four discs includes: 1 soft and 1 medium rubber covered foam discs for quieter volumes and looser batter feel; 1 medium and 1 hard patented polymer covered foam disc for medium and loud volumes with medium and tight batter feel. These are all quieter than the maximum volume achieved by removing all discs from the impact area.