Originally Posted by cosmotini
I asked about this one time and was told that only the Classics have the valves with the remote sensors. The monitor has the ability to report the propane levels, but the valves used in the Internationals and Safaris don't have the remote sensors.
I believe it requires a two-port tank. The sensor is much like the OPD valve, a float that reports liquid level. You can get them equipped to either read at the tank or read remotely, same price. I believe Vintage Trailer Supply sells them (best source for aluminum tanks that I know of).
There are a bit pricey, so I think a good strategy is to have one with the sensor and always use that one as your second tank. If you have an auto-switchover regulator, that second tank would give you plenty of warning on running out.