I've been using these wireless
I've been using these wireless tags for 4 or 5 years. Since they originally came out. We use them to monitor the systems on our 47' sailboat that is 200 miles away. This is a PERFECT solution for us - we know the status of our refrigerator, freezer, battery compartment, HVAC units, engine and generator exhaust. We use the moisture sensors in our bilge and on deck compartments to let us know when we might have an inoperable bilge pump or a clogged drain. Finally, we use the motion detector (formerly we used the reed sensor) to see when anyone gets on board. We just love them.