Futaba FU1K12901 D5mm Servo Horn Circle 2pcs for S3103/S3107/3153/3156/3157  [FU1K12901]

Futaba D5mm servo horn circle

This Futaba FU1K12901 D5mm servo horn circle is an RC-scale servo accessory supplied as 2pcs, intended for direct replacement or tuning of compatible servo arms on the listed Futaba-compatible servo models. The listing specifies it comes without packing and without screws, so fasteners and any mounting hardware must be provided separately.

Compatibility: the item name lists S3103, S3107, 3153, 3156, and 3157 as compatible models. Confirm spline and D5mm fit on your servo before installation to ensure proper engagement and range of motion. Do not assume fit on other servo types not listed.

Installation and tuning role: remove the original servo arm, fit the D5mm horn circle onto the servo spline, align the arm position for neutral travel, and secure using an appropriate screw or retaining method you supply. The part serves as a linkage point for servo arms and is useful when fine-tuning throw or changing leverage for steering or control inputs on small RC models.

Practical notes: this is a basic replacement/tuning component for model-level work, not a complete servo assembly. Use threadlock or locking methods appropriate for your setup if needed, and verify end-to-end travel after installation to avoid binding or overtravel.