The metal-sandwich'd Double Horse 9104 rotor Head assembly. The buckle links are substantial, and the small diameter swash makes the servo's inputs a little less aggressive getting to the flybar. Also notice the "wrong" angle on the servo link, likely another intentional effort to tame the copter's overall response.
In the short hops I gave it, there was a lot of "give" in the F/R control, it did not feel twitchy.
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