This is Xpert WR-7701-HV Standard Size Waterproof Servo.
 Features
  - IP67 certified fully waterproof design
  - Brushless motor design provides extremely high speed, and low power consumption.
  - 4096 resolution and SIC (Single Integrated Circuit) for the highest performance and durability.
  - Plastic upper and lower with aluminum middle case for optimized thermal dissipation and durability.
  - 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: .196 sec/60° 
  - @7.4V: .158 sec/60° 
  - @8.4V: .14 sec/60°
  
 - Torque (oz/in): 
   - @6.0V: 307.3 oz-in 
  - @7.4V: 379.06 oz-in 
  - @8.4V: 430.28 oz-in
  
 - Torque (kg/cm): 
   - @6.0V: 22.14 kg-cm 
  - @7.4V: 27.31 kg-cm 
  - @8.4V: 32 kg-cm
  
 - Dimensions: 40x 37.8x20 mm
  - Weight: 70.3 g
  - Frequency: 200/300 Hz
  - Range:50~400 Hz
  - Center Position: 1520us
  - Applications: 1/10 & 1/8 Surface