Mercury - GPS Add-In Kit Rigging Accessory 8M0134384. OverviewThis GPS add-in kit gives your boat a steady GPS signal without adding much complication to the rigging. It plugs into the system with a simple harness and starts feeding clean data as soon as it powers up. On the water, the signal hangs on even when the boat's moving around, which helps the rest of your SmartCraft features behave more predictably. It's a small part, but it smooths out a lot of little quirks.. Key Features • GPS Modul