This metal gear RC servo with 17kg.cm holding torque is a heavy duty solution for student robotic projects whom build arms or linkages that required high torque. The advantage of RC servo over the DC brush motor is the ability to control its rotation angle. 

Specification:
Origin: China
Metal gears
Torque(4.8V) : 15.5 kg-cm (215.3 oz/in)
Torque(6.0V) : 17.0 kg-cm (236.1 oz/in)
Speed : 0.16 sec (4.8V) | 0.14 sec (6.0V)
Operating Voltage : 4.8 ~ 6.0 DC Volts
Weight : 63.0 g (2.22 oz)
Bearing Type : Ball Bearing x 2
Motor Type : DC Motor
Gear Type : Copper
Operating Temperature : -20ºC~60ºC
Working frequence: 1520µs / 50hz
Size : 40.7 x 20.5 x 39.5 mm ( 1.60 x 0.81 x 1.56 in)
Rotation angle: 180 degree
Package includes plastic servo horn and accessories