S9257 High Speed Ball Bearing Nylon Gear Digital Micro Servo from Futaba - FUTM0667
This is the Futaba S9257 high speed digital servo for helicopter gyro operation. Works with the GY502 gyros. Also can work for 1400 to 2000mm wingspan airplanes, medium and large EDF jets, and 500 sizes helicopters.
Features:

For use with the GY502 gyros
Equipped with two ball bearings
High speed
One year warranty

Includes:

1x S9257 high speed ball bearing nylon gear digital micro servo
1x .83" (21mm) diameter round horn
1x 1.5" (39mm) diameter four-point horn
1x 1.2" (32mm) diameter six-point horn
1x mounting hardware