This is the HS-7940TH High Speed, High Torque Digital Servo from Hitec.
Ideal for larger helicopters and cars needing high speed and plenty of torque. Coreless motor for precise centering and accuracy.
Size : 1.57 x 0.79 x 1.50" (40 x 20 x 38mm)
Weight : 2.40oz (68g)
Speed : 6.0V /0.07 sec and 7.4V/0.06 sec
Torque : 6.0V/181 oz/in (13.0kg/cm) and 7.4V/222 oz/in (16.0kg/cm)
Drivetrain Type : Dual ball bearing