JD now offers the same thing on the Bullet Rotor.Kuchar also offers it for the STS[not a rotor].John Deere came out with it after the aftermarket companies did.
Whose brand are they, and what do they look like. The JD ones I have seen don't run the teeth open all the way through, but only have two small openings along the back, which they say is for threshing rice.