what sensor is this?

Recently did my back brakes for the 1st time, usually i just let my dad do it at his job since he's a mechanic. Anyway, whats the sensor near the calipers in the rear? had one by each rear caliper.

Thanks

I believe its for the ABS system

Correct. wheel sensors for the ABS System.

A 4 channel ABS system will have 2 sensors in front and 2 in back. F-bodies with the 4 channel system are equipped with TCS. It sounds like your car is a 4 channel car.

Cars without TCS are 3 channel cars. They only have one sensor in the back, up on the top center of the differential. My cars are both like this.

Cars without TCS are 3 channel cars. They only have one sensor in the back, up on the top center of the differential. My cars are both like this.
Mine is like this too. It is basically a magnet sensing the rotation of the gears, once the gears stop the ABS kicks in.

The tone ring in the wheel speed sensors send an AC current back to the computer to keep check on the varying speeds, and will then makes the brakes pulse if it senses a wheel is slipping.

:)