This motor is the same MG996R but modified to operate as a continuous rotation motor which makes it perfect for robotics projects, but at the same time this means that it is not possible to control the motor shaft position, only the direction of rotation and speed.

NOTE: This is a continuous rotation servo. 

Adafruit Explanation of Continuous Servos

Specifications

• Weight: 55g
• Stall torque: 9.4kg/cm (4.8v); 11kg/cm (6.0v)
• Operating speed: 0.19sec/60degree (4.8v); 0.15sec/60degree (6.0v)
• Operating voltage: 4.8~ 6.6v
• Normal operating current: 600mA - 1A
• Stall current: 2.5A
• Gear Type: Metal gear, upgraded gear set and shaft to aluminum 6061-T6 which makes it stronger and lighter than copper.
• Temperature range: 0- 55deg
• servo wire length: 30cm
• It’s universal “S" type connector that fits most receivers, including Futaba, JR, Hitec ,GWS, Cirrus, Blue Bird, Blue Arrow, Corona, Berg, Spektrum.
• CE &RoHS approved

Product includes

• 1 X MG996R continuos rotation servo motor
• 1 X set of servo arms and screws 

Dimensions

A(mm)  42.7  B(mm)  40.9  C(mm0  37  D(mm)  20  E(mm)  54  F(mm)  26.8