Pacific Dualies 90708 PressurePlus 8000 Series 2-Sensor Expansion Kit for 4th Axle, Sensor # 7 & 8 2 sensor expansion kit for 4th axle with No.7 and No.8 sensors for PressurePlus 8000 series TPMS system Monitors tire pressure and temperature on an easy to read display with no additional repeater necessary Tire sensors are easy to install and O-Ring sealed and include locks to prevent theft Sensor batteries are included