This is the Hitec Standard Metal Servo Horn.

FEATURES: 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.

INCLUDES: One Hitec Standard Metal Servo Horn

REQUIRES: Attaching to output shaft with phillips screw (not included).

SPECS: Length from center: 0.87" (22mm) Thickness: 0.08" (2mm) Diameter of center hole: 0.22" (5.5mm) ir/kh  

BOX DIMENSIONS: 2.38" W. X .25" H. X 3.00" L. BOX WEIGHT: .01 LBS.