Futaba FU1K12901 - D5mm Servo Horn Circle (2pcs) compatible with S3103/S3107/3153/3156/3157  [FU1K12901]

Replacement D5mm Servo Horn for Listed Futaba Models

This Futaba FU1K12901 D5mm horn circle is supplied in pairs as a replacement or tuning accessory for the specified Futaba servo models. Note that the product is supplied without packing or fixing screws, so you will need to provide the appropriate mounting hardware.

Compatibility details: S3103, S3107, 3153, 3156, and 3157 are shown as compatible in the name. Verify the spline type and D5mm diameter on your servo before installing to avoid misfit or restricted motion. Do not fit to servos that are not listed without checking dimensions.

Tuning and installation: remove the stock arm, press the D5mm horn onto the spline, set the arm for neutral travel and secure it with a suitable screw or retention method you supply. The part is useful when altering throw or mechanical advantage for steering and control inputs on small RC rigs.

Workshop tips: this is a component-level replacement, not a full servo. Apply threadlocker where needed and confirm full sweep after installation to ensure there is no binding or overtravel.