This is the Futaba BLS254 Brushless Heli Rudder 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 Standard size Equipped with two ball bearings 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 INCLUDES: Futaba BLS254 Brushless Heli Rudder Servo with universal connector (21mm) diameter round horn, 1.8" (45mm) diameter round horn 1.2" (32mm) diameter 6-point horn, 1.5" (38.8mm) diameter 4-point horn mounting screws, eyelets and grommets REQUIRES: Installing in heli, connecting linkage and connecting to receiver SPECS: Torque: 53 oz-in (3.8kg/cm) @ 4.8V Speed: 0.06 sec/60° @ 4.8V Size: 1.60 x 0.80 x 1.50" (40 x 20 x 36.8mm) Weight: 1.80 oz (51g) Pulse width: 1520 jxs 6/24/09 ir/jxs