Mercury - MP Alert Replacement Light (Oval) Service Part 8M0109506. Overview. The Mercury 8M0109506 MP Alert Light is the direct service replacement for the oval-style smart lights used in the Moving Prop (MP) Alert system. If an existing light becomes damaged, dim, or fails after long-term exposure to sun and spray, this replacement restores full visibility and keeps the MP Alert system working exactly as intended. It installs quickly and plugs into your existing MP Alert harness with no modifi