This is the Hitec Standard Metal Servo Horn.
Single arm style constructed of blue anodized aluminum with four
pre-drilled linkage holes.
Fits Hitec servos that have a “+” stamped on top of the output shaft
or any brand servo with a 5.5mm diameter output shaft.
One Hitec Standard Metal Servo Horn
Attaching to output shaft with phillips screw (not included).
Length from center: 0.87″ (22mm)
Thickness: 0.08″ (2mm)
Diameter of center hole: 0.22″ (5.5mm)