This is the Futaba BLS257 Brushless Rudder Mini Digital Servo.
When using with the GY520 you must make sure you change to
the correct mode in the gyro software.

FEATURES:
Designed for 3D helis
30% faster response than standard digital servos and five times
longer lasting than servos with brushed motors
Same power consumption as brushed digital servos
One year limited warranty through manufacturer beginning at date of
purchase


INCLUDES:
Futaba BLS257 Brushless Heli Rudder Mini Digital Servo with
universal connector, 0.83" (21mm) diameter round horn, 1.2" (32mm)
diameter 6-point horn, 1.5" (38.8mm) diameter 4-point horn, four
each mounting screws, eyelets and grommets


REQUIRES:
Installing in heli, connecting linkage and connecting to receiver


SPECS:
Torque: 36 oz-in. (2.6 kg-cm) @ 4.8V
Speed: 0.07 sec/60¢X
Size: 1.4 x 0.6 x 1.1" (35.5 x 15 x 28.6mm)
Weight: 0.92 oz (26g)