The capacity of a pressure pump is generally the best indicator of an espresso machine’s brewing potential—the higher the pressure, the better the flavor. A good espresso maker should be able to generate at least 15 bars for the optimal coffee processing, though this level of steam pressure is only the lowest margin required for brewing decent espresso. Appliances with pressure pumps that exceed 15 bars often feature a built-in gauge to indicate the pressure generated by the pump during the cycle. These espresso makers show even more promise in extracting the best possible flavor and aroma from fresh and pre-packaged grounds, and this is precisely why they tend to be so expensive.