This is the Savox SH-1290MG Digital Metal Gear Ultra Speed Servo.

Features:

• Super High Resolution
• Water-Resistant w/4 silicone seals
• Coreless Motor provides high speed, incredible efficiency, and low power consumption
• The Aluminum Case design not only looks good but also allows for lower operating temperatures.
• Totally Green – from materials to production, these servos are environmentally friendly.
• Ideal as a rudder servo on 500, 600, and 700 class helis

*NOTE: Certain combinations of receiver and ESC have been found to cause "Brown Out" issues when combined with Savox servos. An external BEC or BEC stabilizing receiver capacitor may be needed for efficient, glitch free operation in low voltage electric applications. 

Specifications: 

• Speed @ 6.0V: 0.04 sec/60°
• Torque @ 6.0V: 69 oz-in / 5 kg-cm
• Weight: 56.4g
• Type: Standard
• Gear: Metal
• Case: Aluminum Heatsink
• Case Size (LxWxH): 40.3x20x37.2mm