Be warned: I bought the conversion kit thinking it would work with these MBS all-terrain wheels... it does not.

https://www.amazon.com/MBS-All-Terrain-Longboard-Wheels/dp/B074G95LP5

Apparently it previously did, but MBS changed their core design. I was advised by SR that I can make the conversion kit pulleys fit by slightly filing down the pieces that fit into the wheel core) but I assume that might make it an insecure fit for their wheels such as the Foamies.