That piece is the aluminum servo shaft to 4.7 mm steel D-shaft axle adapter that's included in the TETRIX MAX Standard Servo Mounting Kit (www.tetrixrobotics.com/TETRIX-MAX-Standard-Servo-Mounting-Kit). It's a specialty servo horn that connects the axle directly to the servo.
What is the piece that connects the servo to the axle? It looks like just an axle connector, but how does it mount to a servo horn?
That piece is the aluminum servo shaft to 4.7 mm steel D-shaft axle adapter that's included in the TETRIX MAX Standard Servo Mounting Kit (www.tetrixrobotics.com/TETRIX-MAX-Standard-Servo-Mounting-Kit). It's a specialty servo horn that connects the axle directly to the servo.