Semi-automatic espresso machines are electric pump machines that were first introduced by Gaggia in the 1940's. They succeeded the Pistol machine mainly because of their comparative ease of use. The electric pump was easily able to produce the necessary pressure without the inconsistencies inherent of the human powered pistons. This system quickly replaced the Piston Style espresso machines and became the method of choice for cafes, food services and the home. Semi automatic espresso machines operate in what we call the semi automatic mode. This means that the user starts the pump with an on/off switch and stops the pumping action when the extraction is complete. The extraction takes about 20 to 25 seconds so the user will wait for the coffee process to finish and then switch off the machine. Ease of use is good and the learning curve is average. This is the most popular style of machine for use in the home. These machines are more consistent and simpler to use then the Piston Style units and will also produce an excellent product