This is the Futaba BLS257 Brushless Rudder Mini Digital Servo.

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 mounting screws, eyelets and grommets

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