It looks like a micro servo, it acts like a micro servo, but it's more than just a micro servo! Adafruit got a factory to custom-make these quality metal-geared 'micro' sized hobby servos with a twist - the feedback (potentiometer wiper) line is brought out to a fourth white wire. You can read this wire with an analog input such as those on an Arduino, to get the servo's position. That information can be used in robotics to improve stability or even allow 'recording' of servo motion.
Check out Adafruit's example Arduino sketch which demonstrates how to record motion data to the EEPROM and then play it back when a button is pressed. Comes with a range of horns as seen above.
Analog Feedback Micro Servo - Metal Gear (12:41)
- Dimensions: 11.58mm / 0.45" x 22.75mm / 0.89" x 29.19mm / 1.14"
- Max Dimensions: 11.58mm / 0.45" x 32.74mm / 1.28" x 31.19mm / 1.22"
- Wire length (at least): 131.67mm / 5.18" long
- Torque: 25 oz*in / 1.8 kg*cm @6V
- Speed: 0.1 sec/60° @6V
- Weight: 15.81 grams
- Dual ball bearing
- Metal gearbox
- Approx 120 degrees of rotation (500 to 2500 microseconds)
- Spline Count: 22