This is the Spektrum RC 18Kg Steel Gear Servo.
Specifications:
Product Width: 0.79" (20 mm)
Gear Type: Metal
Input Voltage: 6.0v-7.2v
Part Type: Electronics
Product Height: 1.55" (39 mm)
Spline Count: 23 - Tooth
Maximum Servo Torque: 229oz-in, 16.49kg-cm at 6v, 263oz-in, 18.94kg-cm at 7.2v
Servo Operating Voltage: 6.0 - 7.4V (HV)
Product Length: 1.58" (40 mm)