Servo horn overview: this is an optional ecopower aluminum clamping servo horn, intended for use with ecopower 860t servo along with other 15t splined servos. This extremely tough servo-horn has been machined from a solid block of aluminum for incredible precision, rigidity, and durability. The horn features a clamp type design that grips the servo’s output shaft so if the retainer screw comes loose, the horn will have a better chance of remaining in place, increasing your chances of finishing the race! Features: clamping design 20mm, 25mm and 30mm hole spacing (measured from output shaft screw hole, to linkage rod holes, center to center) dimensions (lxwxh): 43x12x8. 5mm 5mm thick arm 15t spline ecopower output shaft linkage holes threaded for 4mm hardware includes: (1) servo horn (2) 3x8mm screws (ecp-3112)