Tall motor brush (.589 inches wide or between 9/16 and 5/8 inch) for the D4 SE (Special Edition) motor design that became effective serial number 7520715 and fits the R5124 tall brush holder. Cannot be used with the older armature design that uses the shorter motor brushes.
At one point, Rexair manufactured a high-amp motor brush (R6592) but on September 19th 2000 they discontinued due to the grade of carbon no longer being available. If you have already replaced your carbon brushes before and are unsure if you have the standard or hi-amp motor brushes, Rexair recommends you replace these in pairs so not to mix with the R6592.
Not properly seating in the carbon brushes can cause brush and commutator damage leading to costly maintenance and downtime
By properly seating in the carbon brushes, it allows you to use rated current almost immediately
Change all carbon brushes at one time
Vacuum excess carbon dust to prevent from reaching machine windings and bearings

The M596 Seating Stone is only used to "clean up" the commutator of the armature and not meant to "seat" the brushes.
If you do not seat the motor brushes, you can expect about a one year life before they wear out.