It's made by Vena, and it also has your DC volts continuously displayed. It's extremely accurate and if you have the right propane tanks, (I do not) it will even monitor your propane levels.
You have to attach sensors to each tank, it takes 4 for our Montana's, (The kit only comes with 3, I had to order another sensor-$10.00)
Simple to hook up, great directions.
I have to get my last sensor and then calibrate the system, I'll let you know how it works. I think it was a couple of hundred smakers.
Ozz
On edit, it has a water pump switch as well, I left my old monitor system intact as a back up, I had to have the water heater switch anyway.
http://i7.tinypic.com/21e41o8.jpg