Compatible with Flame King Mountable RV ASME Tanks with bolt-on gauge. It is very easy to install via the Bolt-On Attachment mechanism. Dial indicator shows the propane level through a built-in 0-90 ohm magnetic black sensor. It works by varying electrical resistance in proportion to the propane level inside the tank; the resistance range used by the sensor matches the RV tank gauges or monitoring systems. At full capacity, the sensor will register close to 90 ohms of resistance; at empty, the resistance often drops near 0 ohms; the monitoring system converts this resistance value into a readable fuel level display. This sensor should be wired to a central monitoring panel inside the RV to provide real-time propane level updates for convenient tracking.