This is the Xpert RC SI-4401-HV Standard Size Aluminum Servo.
 Features
  - Brushless motor design provides extremely high speed, and low power consumption.
- 4096 resolution and SIC (Single Integrated Circuit) for the highest performance and durability.
- Aluminum middle case for optimized thermal dissipation.
- Strong All Metal Gear
- Glitch-free
- Sophisticated error correction
- High-Speed, High-precision 12-bit AD converter and CPU calculation
- Fail safe
- Over current protection
- Over temperature protection
- Start sonorant
 
 Specifications
  - Power Supply: 6.0V~8.4V
- Speed (sec/ 60°): 
 - @6.0V: .111sec/60°
- @7.4V: .090 sec/60°
- @8.4V: .079 sec/60°
- Torque (oz/in): 
 - @6.0V: 186.41 oz-in
- @7.4V: 229.85 oz-in
- @8.4V: 260.94 oz-in
- Torque (kg/cm): 
 - @6.0V: 13.43 kg-cm
- @7.4V: 16.56 kg-cm
- @8.4V: 18.80 kg-cm
- Dimensions: 40x37.80x20 mm
- Weight: 62.50g
- Frequency: 200/333 Hz
- Range: 50~400 Hz
- Center Position: 1520us 
- Applications: Helicopter Cyclic
- Matching Gear replacement: XGS72320
- Matching Case: XP-01