This device is intended to do the "heavy lifting" when grounding a points-style magneto for the purposes of limiting engine speed.
The pigtail included will help you plug into a standard molex plug used on all crank trigger pickups.
The green wire is ground from the pickup and the violet wire is the signal. Use this to connect the pickup to your RPM activated switch.
If your magneto is an internal coil (OAC) Vertex, you can use this too! The positive wire would go to the primary side terminal on the mag. Instead of attaching the black wire to the negative coil terminal as shown, just attach it to engine ground.
Click here for a printable schematic!