This is the Futaba BLS251 Brushless Digital Heli Rudder Servo.
           Designed specifically for helicopter rudder operation.
***Compatible with the Futaba GY520, GY601, GY611 and GY701 gyros.***
This servo can produce high-current draw from your batteries.If using
NiMH or LiPo batteries, make sure they are capable of delivering sufficient amps.
FEATURES: Equipped with a Brushless motor that lasts longer and operates at a
lower temperature than Brushed motors Samarium Cobalt magnets and dual ball bearings
30% faster response times, smoother operation.
Same power consumption and centering as Digital servos equipped with
-Brushed motors
-Metal gear
Compatible with Super Narrow Pulse of (760µs) drive.
INCLUDES: Futaba BLS251 Brushless Digital Heli Rudder Servo with universal
1.8" (45mm) diameter round horn
1.2" (32mm) diameter 6-point horn
1.5" (38.5mm) 4-point horn
Servo mounting hardware
REQUIRES: Installing in helicopter and plugging into gyro
SPECS:    Torque @ 4.8V: 53 oz-in (3.8 kg-cm)
Speed @ 4.8V: 0.06 sec
Dimensions: 1.6 x 0.8 x 1.5" (40 x 20 x 36.8mm)
Weight: 2.1oz (59.5g)