This is the Hitec HS-7956SHR Digital Rudder Servo with Tray.

FEATURES: Designed for 20-120 size gasoline aircraft
          All-in-one aluminum rudder tray integrated with top case of servo
          Large size ball bearing for 3.5" (89mm) rudder horn
          Aluminum turnbuckle pull-pull wire tensioner
          2S Lipo or 6-cell NiMH compatible
          Steel gears with dual ball bearings
          Programmable G2 digital amplifier with MOSFET drive (requires Hitec
            Servo Programmer, sold separately HRCM4420, HRCM4421)
          Center case heat sink
          Water and dust resistant

INCLUDES: HS-7956SHR Digital Rudder Servo with Tray, Pull-Pull Wire Tensioner,
            two Ball Links, two Turnbuckles and Mounting Hardware

SPECS:                              6V              7.4V
          Operating Speed:  0.15 sec/60°          0.12 sec/60°
          Output Torque: 277.74oz.in (20kg.cm)    340.24oz.in (24.5kg.cm)
          Weight: 2.40oz (68g)
          Dimensions: 1.57 x 0.79 x 1.45" (40 x 20 x 37mm)

                                                                   jxs 03/05/13
                                                                         ir/jxs