If you use rotary often, I'd suggest picking up a bottle of this stuff. It gives you a more "oily" compound then that of the rupes da course which allows you to work the compound longer without it dusting. When I first purchased this to test I was skeptical so I tried both the rotary course and da course side by side and came to this conclusion; if you don't use rotary often then you can get away with using the da course but the user experience won't be as good and the result may suffer slightly as well, but if you reach for the rotary often then it's worth having this on hand, the user experience is much nice with quicker results, and I find less fatigue on the user. I personally have both in my system, rupes da course and rotary course.