Mercury - Moving Prop Alert Light System (Oval) SmartCraft Safety Kit 8M0109507. Overview. A spinning propeller can be hard to see in the water-especially for swimmers, divers, or family members near the transom. The Mercury 8M0109507 Moving Prop Alert Light System adds a bright, unmistakable visual warning that activates automatically whenever the prop is in motion. Designed for SmartCraft-compatible engines, this oval-style kit uses dual LED smart lights and a control module linked directly to