This is the Futaba GY401 Gyro
This is a high performance, compact and lightweight (AVCS) Angular Vector Control System gyro developed for model helicopters.
Because the sensor and control circuit are integrated, it is simple to install.

FEATURES:

• AVCS System: Since the rudder trim changes (caused by wind and other meteorological changes) the front, rear, and other heli attitudes change and are automatically canceled; tail (rudder) operation is easy, making it perfect for 3D flight. (also known as heading hold gyro)
• SMM Gyro Sensor: Use of this newly developed technology virtually eliminates rudder trim changes during flight.
• Digital Servo Compatible (DS Mode): DS mode makes it compatible with Futaba digital servos. This maximizes the high-speed response performance of the digital servo.
• Remote Gain Function and Mode Switching Function Remote: Gain function allows sensitivity switching from the transmitter and mode switching function allows AVCS/normal gyro mode switching.
• Integrated, compact and lightweight design made possible by high density mounting technology.
• Conductive Resin Case: This case improves EMC (Electrostatic and electromagnetic interference) resistance.
• One year warranty
  

INCLUDES:

• One GY401 gyro
• One mini plastic adjustment screwdriver
• Three mounting pads
• One instruction sheet
  

SPECS:

• GY401 Gyro
• Length: 1.1" (27mm)
• Width: 1.1" (27mm)
• Height: 0.79" (20mm)
• Weight: 0.95oz (27g)