Metal Oxide Semi Conductor Field-Effect Transistor or MOSFET, is a three terminal device that has applications in Airsoft as a switching device.
A side benefit of installing a MOSFET into an airsoft gun is the improvement felt in the trigger response. MOSFETs are able to switch the resistance in the circuit very fast relative to the input voltage. Combined with the more stable transmission of charge particles it provides, the MOSFET is able to route a lot of current very quickly.
Additional functions like active braking, pre-cocking, different burst modes, and other behavioral functions can be programmed into certain models at additional cost. Because of this, considerable thought needs to go into deciding the type of MOSFET that bests fits the desired application.