The airsoft spring is the true power source of an airsoft gun as an immense amount of energy is released by the compression and stretching of a coiled spring. They come in different ratings from M90 to M180 that reference to its tension strength. The stronger the spring, the more power it can output, thus yielding a higher FPS output. Whether downgrading or upgrading to a desired FPS level, choosing the spring that best suits your airsoft gun is important as a stronger spring will require a stronger gearbox and battery.
