A good number of digital ignition systems make use of this switch format. Basically, you use a small screwdriver (supplied by MSD for their system) to set the respective values. What can you set? In this system, two built-in rev limiters, a single-stage retard, adjustable magnetic pickup compensation, and a LED display that warns of trigger signal problems or a faulty charging system are included. All of the adjustable features use a rotary switch to change the values in 100-rpm increments. In the past, these features mandated the use of a number of specialized add-on boxes. Thanks to digital electronics, they are now all included in one easy-to-adjust package.