Wireless Battery SensorMonitor battery voltage with the Wireless Battery Sensor, and never worry about a dead battery again. Attach the Battery Connect to one of the boat’s batteries and plug the other end into the Wireless Module. Link the module to the MTC and receive alerts if the battery voltage exceeds or drops below a preset level. Ideal for monitoring multiple batteries on a boat.C. Includes: Wireless Sensor Module Battery Connector 3 feet of wire