This is the Savox SA-1230SG Monster Torque Steel Gear Digital Servo. 
Features:
- Combines leading edge technology with super high 12 bit (4096) resolution and unique steel gears.
- Super light-weight.
- Coreless motor provides extremely high speed, incredible efficiency, and low power consumption.
- Extremely strong unique steel gears ensure long-life and durability.
- The full aluminum case design not only looks good but also allows for cooler and smoother operating temps.
- Ideal for giant scale aircraft, monster truck, 1/8 scale.
Specifications:
- Dimensions(:mm): 40.3x20.2x45.0
- Weight(g): 79.0
- Speed(@4.8V sec/60): .20
- Torque(@4.8V oz-in): 416.6
- Speed(@6.0V sec/60): .16
- Torque(@6.0V oz-in): 500.0
- Gear: Unique Steel
- Bearing: 2BB
- Case: Full Aluminum
- 25 Tooth Spline
- Frequency: 250-333hz
- Pulse Width Frequency: 1520
Used with permission, copyright 2017 Brey Corp. t/a Hobby Works