This is the GY401 Gyro with SMM Technology from Futaba.
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 cancelled; 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 (see COMMENTS).
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.

INCLUDES:
One GY401 gyro
One S9254 Digital servo
One .81" (20.5mm) round servo horn, one 1.8" (45mm) round servo horn
One 1.25" (32mm) 6 point servo horn, one 1.5" (39mm) 4 point horn, mounting hardware
One mini plastic adjustment screwdriver
Three mounting pads
One instruction sheet

SPECS: GY401 Gyro-
Length: 27mm
Width: 27mm
Height: 20mm
Weight: 27g
Voltage- use only with a 4.8V battery. (if you use it with a higher voltage battery it needs to be regulated to 6V) S9254 Digital Servo -
Length: 1.6" (40mm)
Width: .79" (20mm)
Height: 1.4" (36.2mm) not including horn
Weight: 1.8oz (50g)

COMMENTS: Can be used in helicopters and airplanes (Due to 0-100% Gain Adjust). The new SMM (Silicon Micro Machine) technology is the integration of mechanical elements, sensors, actuators and electronics all brought together on a common substrate chip. This hobby industry first, results in a gyro sensor with an unprecedented level of functionality, reliability, and sophistication. This will not work with the JR Digital Servos. These have a different pulse. Voltage- use only with a 4.8V battery. (if you use it with a higher voltage battery it needs to be regulated to 6V)