This is a sail servo arm that fits on the S3801 servo.
Features: Black plastic construction
Includes: 1 servo arm
Overall Length: 4 7/8
Hole to hole: 3 15/16 & 4 1/4 (from center of hole where attaches to servo to the centers of the linkage holes)
Widest Point: 7/8 (where mounts to servo)
Narrowest Point: 3/8 (furthest away from servo)
Note: This fits any Futaba servo, but may hurt gearing on high-torque applications. Since the S125 has a square spline this arms will not fit without an adapter, which we don't carry at this time.