The package was simple to open and review its contents. It came with 2 magnetic tank sensors and 6 metal clips for the bottom of the tank. I was excited to try this product because I had already bought magnetic strips that attach to the side of the propane tank, which supposedly change color as the propane level drops along their indicator markings. They didn't work at all.
I had some deja vu, however, when the app I downloaded, Tank Check, didn't connect to the sensors after following the directions both in the packaging and on the app. The app had a spinning icon saying it was scanning for the devices, and that continued for several minutes without success. At first I thought they might have dead batteries -- I've come across that before -- but my multimeter proved that to be incorrect. I re-installed the disk batteries, put the covers back on and tried again. My wife joined me and noticed that a couple of instructions ahead said to press the sync button 5 times after it connected, so we did that, before it connected, and voila, up came each one onto the app. After that, everything worked perfectly.
We then installed the metal clips to the bottom of the tanks' base in order to lift the tank slightly off of the flat floor of the compartment so that there would be more room for the sensor once applied to the bottom of the tank. There were a lot of negative comments about these clips, which evidently may have been plastic in the past, but these metal clips worked fine.
I placed the magnetic sensors on the bottom of each tank and checked the app. Sure enough, the full one showed 100% and the mostly empty tank showed at 28%. The app lets you name the tank and select the size among 20, 30 and 40 pounds, and once I selected 30 for my tanks, the monitor changed that level to 23%. I replaced the tanks in their compartment and went inside the rig, and the monitor app worked fine.
There is a hardware monitor you can purchase if you didn't want to use a phone app, and I'm pretty certain the app is available for both Apple and Android phones (mine's a Moto Z). One other drawback was that once the sensors were connected to my phone, my wife could not connect to them. That means if I'm not around, she can't monitor the tank levels. Not a big deal, but it is a small annoyance.
Overall I'm impressed with the product and highly recommend it. It's long been a pain having dual propane tanks without knowing the propane levels. I'm happy that is no longer the case. You can purchase the tank monitor from Amazon at the link below.
The Tech Support department from the manufacturer contacted me to clear up a couple of things. First, regarding multiple devices syncing up with the sensors:
"The sensors can be paired to as many phones and monitors as you like. If your wife downloads the app, then opens it the scanning icon will spin, when that happens press the "sync" on the sensor again and it should pair to her phone. They will communicate to your phone, the monitor, and her phone as well with the same reading. Any phone after an I phone 4S or a Galaxy 4 would be able to pair no issue."
Then, to answer a question in the comments below about whether the devices would be okay to use if the propane tanks were on the tongue instead of a compartment:
"The magnets are rated at 3# each and there are multiple sensors are installed on motor home tanks as well, so they are exposed to rain and tire wash daily. They are sealed from the elements, and Mopeka has them warranted for this type of exposure as well. You are correct on the support feet, they were made from a rubber, now they are metal to solve the customer concern and feedback we received. "