Just a note for folks, we’ve been experimenting this these brands of sensors and found a defect in the electronics of a particular manufacturing batch.
The batch of devices manufactured during 1215 have defective electronics and will NOT work properly. They will either fail to register a wet signal or fail to return to a dry signal. We have tried about 7 different devices from this batch and ALL of them have failed in the exact same way. The signal gets stuck either in “wet” or “dry” mode.
So if you’re planning on buying these sensors (which are REALLY good otherwise and have EXCELLENT battery life), do AVOID the 1215 batch. Can confirm that the 0615 batch works fine.
The manufacturing batch number is given just above the bar code on the packaging.