VDO Temperature Sender 250F/120C Floating Ground - 3/8-18NPTF 805/1/5. The floating ground allows water or other liquids to pass through it and the sensor is designed to accurately measure that temperature. This temperature sensor by VDO is self-monitoring and automatically resets if it gets too hot. The VDO Temperature Sender 250F/120C Floating Ground is a highly accurate method of measuring temperature. The floating ground prevents the sender from getting too hot when there is no hot liquid or gas in the sender's path. For a reliable way to measure temperature in your boat use the VDO Temperature Sender 250F/120C Floating Ground. Specifications for VDO Temperature Sender 250F/120C Floating Ground: Manufacturer: VDO Color: Black Package Contents: VDO Temperature Sender 250F/120C Floating Ground VDO 323-479: Temperature Sender 250F/120C Floating Ground - 3/8-18NPTF 805/1/5