This is the SH-1257MG Super Speed Metal Gear Mini Digital Servo.

Features:

The coreless motor and light weight design provides smoother, faster, and more efficient operation.
The metal case design not only looks awesome but also allows for cooler and smoother operating temperatures.
Metal gears form a solid framework for precise control and operation.
Supports digital and analog control signals
Ideal for rudder on 450 level helis, CCPM on 500 level helis, and steering servo on 1/12th scale cars.

Dimensions(mm): 35.0X15.0X29.2
Weight(g): 29.5
Speed(@4.8V sec/60): .09
Torque(@4.8V oz-in): 26.4
Speed(@6.0V sec/60): .07
Torque(@6.0V oz-in): 34.7
Gear: Metal
Bearing: 2BB
Case: Aluminum
25 Tooth Spline