Micro Continuous Rotation Servo - FS90R
Good for beginners who want to make stuff move without building a motor controller with feedback & gear box, especially since it will fit in small places. Of course, its not nearly as strong as a standard servo. Works great with the Motor Shield for Arduino, our 16-channel Servo Driver, or by just wiring up with the Servo library.
To control with an Arduino, we suggest connecting the orange control wire to pin 9 or 10 and using the Servo library included with the Arduino IDE (see here for an example sketch). Position "90" (1.5ms pulse) is stop, "180" (2ms pulse) is full speed forward, "0" (1ms pulse) is full speed backwards. They may require some simple calibration, simply tell the servo to 'stop' and then gently adjust the potentiometer in the recessed hole with a small screwdriver until the servo stops moving.