It would be interesting to know the makeup for the abrasive, looks a lot like the 3M "Cubitron".
With other discs like the blue Granate (Fesstool) and others, removing drum sander lines us usually a chore even after I DS sand up to 220.
The purple (lilac?) discs really make quick work of removing the lines and let me get to a finished surface.
Starbond pricing is not bad at all!