The Hitec Robotics Continuous Rotation Servo is a standard servo modified for continuous rotation. As such, the servo does not have any feedback system. The servo is an excellent choice as a replacement to DC gear motors to drive your small wheeled robot. Nylon gears and dual ball bearings on the output shaft make the servo fairly robust, intended to be used for long periods of time.
Control System: PWM with 1500us neutral.
Required Pulse: 4.8-6.0 Volt Peak to Peak Square Wave
These servos are perfect for continuous rotation. Smooth running and seem to be pretty strong. They are worth it if you dont want to modify a regular 90 deg servo