This is the S3107 Micro Servo from Futaba.
This servo is used for R/C Park Flyer airplanes.

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: Delivers excellent torque and speed for its small size, light weight
3-pole motor
Can be used for elevators, ailerons and rudders
One year warranty
Nylon gears
COMMENTS: This servo cannot be used with gasoline engines or large/middle scale gliders or other models that require torque. Use of 6.0V not recommended as this will shorten servo life.
For replacement servo horn use FUTM2005 INCLUDES: One S3107 Micro Servo with Futaba J male connector and mounting hardware
Connector: Male "J" type with approx. 5" wire
Output Shaft Diameter: 5mm
SPECS: Speed: .12 sec/60¦ @ 4.8V
Torque: 17 oz-in @ 4.8V (1.2 kg-cm @ 4.8V)
Length: .9" (23mm)
Width: .4" (10mm)
Height: .8" (20mm)
Weight: .3 ounce (9 grams)