This is the S5301 High Torque 1/4 Scale Servo from Futaba. It is used for R/C airplanes, sailplanes, gas cars and power boats.

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:
Exceptional strength for operating large rudders with ease, and can be used to replace dual servo applications on elevators and ailerons.
5-pole motor
High torque
Metal gear
Dual ball bearing
Dust and water resistant
One year warranty.

INCLUDES:
One S5301 High Torque 1/4 Scale Servo with Futaba J male connector and large pre-installed cross-shaped servo horn
Four brass eyelets
Four large black rectangular rubber grommets
Four 2 x 11mm servo mounting screws
Three servo horns (1 lg. round, 1 lg."X", 1 sm. 6-arm)

SPECS:
Speed: 0.29 sec/60¢X @ 4.8V - 0.23 sec/60¢X @ 6V
Torque: 233 oz-in @ 4.8V - 292 oz-in @ 6V (16.8 kg-cm @ 4.8V - 21.0 kg-cm @ 6V)
Length: 2.3" (59mm)
Width: 1.1" (29mm)