Good, but limited
This base plate does fit the EOS R battery grip nicely. But, to this date there still is no L-bracket adapter, which is a bit disappointing, and it is not compatible with at least the PMG video cage. Wish they would have mentioned that somewhere. Not sure what other parts it is or isn't compatible with. If all you need is the base plate with nothing else attached to it, then it does fit well and is solid.
Reviewed by: (Verified Buyer) Richard Person from California.