Bought the watchman advanced/plus sonic liquid level monitoring device for my oil tank plus their USB Sensit smart wifi tank level receiver to have it as an app on my mobile. The transmitter and the receiver in the wall worked well from the start showing the level in the tank. The USB took a while to sort out and I thought I was going to have to return it but then it worked after numerous attempts to get it to register on their system via my WiFi broadband. The readings did not come through initially but after a few phone calls they sorted out the software problem from their end.