Typical advantages, applications, and mathematics of flueric operational amplifiers are briefly discussed. In that cascaded proportional amplifiers (gain blocks) are the backbone of operational amplifier circuits, their performance is shown. Practical considerations of gain blocks are pointed out, such as signal-to-noise ratio, frequency response, saturation characteristics, repeatability, hysteresis, and so on. Gain block development breakthroughs achieved during the past two years make operational amplifiers highly practical for fluidic control system design. Examples of operational amplifier test performance are shown; the performance is in excellent agreement with the theory.