The optional Yokomo Aluminum Clamping Servo Horn for the Yokomo YD-2 is an aluminum servo horn that allows more direct operation of the servo. The distance from the servo output shaft to the center of the pillow ball attachment hole at the tip is 23mm, and matches the servo shaft spline (25T) made by Futaba and ProTek. It is the best size for touring cars. This part has been anodized black with chamfered edges for added strength and style.