Taken from TEIN's website. I hate to copy and paste, but it really is the best explanation.
The EDFC (Electronic Damping Force Controller) makes it possible for the driver to control the damping force at the touch of a button while in the driver seat. This is accomplished by controlling stepping motors installed on each shock absorber. Because the damping force can be controlled with such ease, the driver can adjust the suspension to suit all road/track conditions. Thus allowing the driver to fully enjoy the driving experience.