This is the Savox SB-2251SG Speed/Torque Standard Brushless Steel Gear Digital Servo. 

Features:

• Versatile balance of Speed & Torque in a Brushless Servo
• Combines leading edge technology with super high 12 bit (4096) resolution and unique steel gears
• Ideal for use in 6.0V applications
• Brushless motor provides longer life and cooler operating temps
• 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
• Our servos are totally green – from materials to production, these servos are environmentally friendly
• Ideal for giant scale aircraft, monster truck, 1/8 scale

Specifications:

• Dimensions(mm): 40.3x20x37.2
• Weight(g): 68.0
• Speed(@6.0V sec/60): .085
• Torque(@6.0V oz-in): 208
• Gear: Unique Steel
• Bearing: 2BB
• Case: Full Aluminum
• Spline: 25 Tooth