Mercury - MP Alert Cowl Kit Moving Prop Safety Add-On 8M0131810. Overview. The Mercury 8M0131810 MP Alert Cowl Kit adds a clear, high-visibility warning to the engine cowl, giving swimmers and riders an immediate visual cue that the propeller is in motion. Designed as part of the Moving Prop (MP) Alert system, this cowl-mounted light makes the warning easier to see from more angles-especially when someone approaches the boat from the rear or sides.. Key Features. Cowl-Mounted Alert Light - Place