This is the Futaba S3003 Standard Servo, which is is used for cars, boats, or where standard servos are used.
This is the replacement for the following servos, S138,S148,S22,S38 and S12.
It can produce high-current draw from your batteries if using NiMH or LiPo, make sure they are capable of delivering sufficient amps.

INCLUDES:
One S3003 standard servo with preinstalled round servo horn FUTM0031
Four brass eyelets
Four Black rectangular rubber grommets (FUTM2348)
Four servo mount screws
One servo wheel 1-3/8" (35mm) in diameter
One X-shape servo arm 1.5" (38mm) across
One star shaped arm 1-1/4" (32mm) across
Nylon gears
One year warranty

SPECS:
Speed: 0.23 sec/60¢X @ 4.8V
0.19 sec/60¢X @ 6V
Torque: 44 oz-in (3.2 kg-cm) @ 4.8V
57 oz-in (4.1 kg-cm) @ 6V
Dimensions: 1.6" x 0.8 x 1.4" (40 x 20 x 36mm) w/o output shaft
Weight: 1.3oz (37g)
Connector: "J" type with approx. 5" lead