This is the Futaba BLS251 Brushless Digital Heli Rudder Servo. Futaba BLS251 Brushless Digital Heli Rudder Servo with universal. Designed specifically for helicopter rudder operation. Compatible with the Futaba GY520, GY601, GY611 and GY701 gyros.
The now famous HK401B is known to have the same characteristics as the Futaba GY401. HobbyKing 401B AVCS Digital Head Lock Gyro. The famous HK401B Hobbyking Gyro. Make sure you isolate your Gyro from vibration.