This part is actually for a nieghbor. But the problem is it runs nowhere. The previous owner cut the wires to the cell, the flow switch and this third "sensor". The sensor was laying on the ground, its round (about 3/4" to 1"), black, with a nipple that points out. Looks like others I have seen pics of that appear to be drilled into a pipe and held on with a hose clamp?
We were tryong to figure it out so we could see what parts of his salt system do and dont work. THen maybe have it running for him in the next month or so.