This is HiTec Metal Servo Horn. This servo horn sits on top of the servo.

FEATURES: Blue aluminum servo horn

INCLUDES: One double servo horn

REQUIRES: Installing on HS-5735MG servo

SPECS: Length: 1" for each side of arm Total Length 2" ir/kh  

BOX DIMENSIONS: 3.00" W. X .25" H. X 5.00" L. BOX WEIGHT: .02 LBS.