Mercury - 1st Mate Passenger's Wearable Fob Kit Safety & Security Accessory 98-8M6007944. Overview. The 1st Mate system watches over everyone on board-not just the captain. The Mercury 98-8M6007944 Passenger's Wearable Fob Kit gives passengers their own overboard-alert wearable so the system can track their status and trigger alarms if someone unexpectedly enters the water. With both a black wristband and a carabiner clip included, each passenger can wear the fob in the way that feels most comfo