Model 420486 (Magneto, red cap]: Circuit is normally open (not complete) with lanyard clip in place on switch. When lanyard is pulled and clip is removed from switch, circuit is closed (complete), allowing grounding to a suitable ground such as a grounding block, the battery, or a suitable area on the engine itself.
Model 420487 (Ignition, grey cap): Circuit is normally closed (complete) with lanyard clip in place on switch. When lanyard is pulled and clip is removed from switch, circuit is open (not complete), resulting in interruption of current to ignition and shutting off engine.