This is the Futaba BLS371SV Brushless S.Bus2 Programmable Digital High Voltage Nitro Car Servo. 

Specifications: 

• Speed:
• @6.0V: 0.09
• @7.4V: 0.075
• Torque:
• @6.0V: 583.3 oz-in (42.0 kg-cm)
• @7.4V: 680.5 oz-in (49.0 kg-cm)
• Size: 40.5x21.0x37.8mm
• Weight: 76g
• Rated Voltage: DC 6.0V-7.4V
• Operating Voltage: 4.8V-8.4V