Takes an input signal that has a range of ±2.5V and converts it to an output signal with a range of 0-2.5V. It has a high input impedance due to the voltage follower stage, so it can be used without severely disturbing whatever is driving it. Fixed resistors can be used to set the reference voltage, however a potentiometer is preferred because it allows fine adjustment to deal with manufacturing differences in parts, and some of the non+ideal effects found in actual op amps (offset voltage, input bias current).
